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| I n f o B u l l e t i n |
| coopsys .net |
July 2003 |
| IB |
In this issue:
Network Storage technology, Battery backups, Windows Longhorn, Teleworking law, Blacklists |
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| **** NewsBytes **** NewsBytes **** NewsBytes **** |
| 419? Ring 999 |
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Fed up with receiving mails asking for "URGENT ASSISTANCE" or "BUSINESS ASSISTANCE"? These euphemisms for swindling you of cash - the so-called '419' scam named after the relevant Nigerian criminal code - should now be reported to your local police station, the idea being that local forces can assess the actual impact of fraud in their area. Realistically though it seems that your friendly Det. Insp. is only going to investigate cases where money has been lost.
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| Infectious support |
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Plenty of virus-laden emails purporting to be sent from support@microsoft.com abounded last month. It's amazing anyone would think the big MS would even use such a simple address, let alone write to an end user, but at least it makes the viruses easy to spot! The W32/Palyh-A virus disguises an infecting "PIF" extension in an attachment. Best practice says block these attachments from coming into your mail system altogether.
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| Insuring against leaving doors open |
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Disgruntled systems administrator John Powell left NMS Services Inc. with a nasty surprise on quitting the company. It wasn't that he had been writing "back door" programs that later allowed him, as an ex-employee, to access NMS systems remotely and destroy heaps of valuable files. It was that the company's liability insurance policy did not cover Powell's subversive acts while he was on the payroll because they caused no immediate harm, and also because a legal exception is triggered when there is total loss. In the final ruling, Powell was convicted, but only just. Source: The Register.
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| Apple G5 takes a bigger bite |
At its San Francisco Worldwide Developers Conference, Apple recently officially released its G5 series of the Power Mac - the first desktop computer powered by a 64-bit processor, making it the 'world's fastest personal computer', according to CEO Steve Jobs. The new IBM PowerPC 970 chip runs at up to 2GHz and takes a 'bigger bite at the apple' by processing a much larger chunk of data at a time than today's 32-bit chips. The spec replaces Megs with Gigs throughout with a high speed 1GHz bus a maximum 8GB of RAM memory. With 7 of the 9 cooling fans running at low speed, the G5 range generates only half the ambient noise of previous Power Mac G4s. Three models make up the range from £1549 to £2299.
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| Munix new systems |
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Munich's mayor has announced a strategic decision that take the city's desktop wholesale into open source territory by converting some 14,000 of its desktop Windows PCs to run Linux and Open Office, from 2004 onwards. Reasons cited are the otherwise expensive upgrades from Windows NT and a desire to move away from single supplier dependency towards an open competitive market as well as being the lowest upfront cost. A special deal on XP by Microsoft's Steve Ballmer failed to persuade the city council in the face of a long-standing arrangement with IBM Deutschland GmbH to supply discounted Linux hardware, software hotline support. Full story: Guardian.
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| Hand to mouth |
Palm's new Tungsten-C handheld will soon allow its users to make voice calls via Internet Telephony. With the addition of VLI's Gphone users can make low-cost or free global phone calls within range of a suitable Wi-Fi network.
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| BT becomes a millionaire |
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BT has succeeded in achieving its Summer 2003 target of one million ADSL connections, coming in closely behind NTL and TeleWest's own combined total of a million cable broadband connections, though this latter includes NTL's controversial 128Kbps cable service which meets Oftel/DTI technical specs, but fails advertising standards.
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| Tube of smarties |
Transport for London (TfL) have finally unleashed on public underground passengers the contactless travel smartcards that have been on test by their staff since last year. As the Oyster smartcards rely on short distance radio signals to communicate with the ticket barrier, they can remain tucked away in a handbag or wallet as the commuter runs hell-for-leather to catch that tube. A&E depts should prepare for a spate of 'crash barrier' type injuries sustained by those who left their smartcard in the other jacket.
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| McAfee release new scan engine 4.2.60 |
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McAfee have released a new scan engine 4.2.60, this is to replace 4.2.40 as it has been known to clear registry key values when 'removing' certain viruses. It is only an interim fix so expect another release soon.
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^ Back to contents ^
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1. Interpreting Network Storage technology
Space to rent?
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More help at hand. All the back issues just a click away
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An historical study by the University of California in Berkeley estimates each man, woman and child on the planet generates the equivalent of 250MB of data each year. In just 12 years, each of us creates as much stored information as it took the whole of humankind 300,000 years to produce.
On a much smaller scale, our own networks are soon outgrown by the proliferation of staff documents, web pages, databases and the like.
Server full! What next?
Once your server disc fills up, it may be time to a install a new one, but that involves a potential migration process, possibly learning a new operating system and becoming accustomed to new hardware.
| "Ninety-three percent of the information produced each year is stored in digital form" |
| Source: Berkeley |
There's an alternative if disc space is your major problem:
Networked Storage
The addition of extra storage may solve your immediate problem and can prove beneficial for accommodating space-eaters like digital photos, layouts, sound and video.
Benefits
- Flexibility - store data where you need it, not necessarily within the confines of your main server hardware, particularly for multi-site organisations
- Scalability - add more space when you want
- Virtualising of resources - treat storage as a 'pool' of space irrespective of the type of device
- Versatility - upgrade to a service supplied by a provider if big storage becomes mission-critical
| SANs versus NAS |
| Storage Area Network |
Network-Attached Storage |
| Good for databases as SANs operate using block handling. Formerly a costly solution but prices are now coming within range of small businesses. Applications can be tied to specific storage resources and backup devices can be linked in. Often linked up with high-speed fibre channel connections for quick access.
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Effectively dedicated, pre-installed file server attaching via a standard Ethernet connections. Easy set up, sometimes via a browser-based interface. The access method usually depends on the operating system the appliance is intended for: NAS file systems for Unix use NFS, and CIFS for Windows uses CIFS (Common Internet File System). Some systems offer file access over HTTP.
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Two technologies have so far defined the market place with disconcertingly similar acronyms - to wit, Storage Area Networks (SANs) and Network-Attached Storage (NAS) - but there are signs these are tending to merge.
The trend is towards a pool of centralised storage, possibly comprised from a mixture of technologies - such as, disc drives, tape backups, CD/DVD - while leaving the processing elements of the main fileserver to service applications, like email and office integration.
High-end enterprises have been implementing this strategy for some time, often based on Sun Microsystems products, but increasing take up and volume is beginning to bring the price down to within reach of smaller companies.
How they work
Network-attached storage (NAS) is basically hard disc storage but defined on its own IP network address - like many networked printers nowadays - instead of being attached to a particular server. 
Attaching the storage directly to the network in this way results in programs and files being delivered to users more quickly faster because they don't have to wait for central fileserver resources, like the processor, to handle those requests - a simple mapping to the NAS file server is all that is needed. The actual storage consists of (preferably fast) hard discs, possibly including multi-disc RAID systems and special software for configuring and mapping file locations.
You couldn't say any of these grey boxes is 'a real looker', but they have the merit of slotting unobtrusively into a rack. Hewlett-Packard's low-cost entry version of its NAS1000s storage devices recently launched with capacities of 320-GigaBytes to 1-TeraByte (1000-GigaBytes) at prices of US$3000 to US$7000.
NAS can be viewed as part of a larger and more sophisticated storage architecture - SAN.
A storage area network (SAN) connects different kinds of storage devices (tape drives, disc drives) together serving a larger network of users - not dissimilar to the data bus inside a PC, in fact.
The storage devices are either close together and interconnected via a high-speed special-purpose network on Fibre Channel technology to large mainframe computers or alternatively may be sited more remotely, providing say, backup and archiving via a wide area network (WAN).
Again, what was once an expensive solution is now beginning to attract lower-cost implementations into the market like Apple's Xserve, a suitable candidate for for smaller businesses.
Thus it's best to think of a SAN possibly incorporating NAS as one of its storage technologies.
Plan ahead
The difference between block-level handling and file interfaces may affect the applications you use at present. An application built over a database like Microsoft's Exchange 2000 works only on block-level interfaces, so check the certification for the products you are considering against your applications.
Technologies like iSCSI are helping to bridge these variances.
Implementing a network storage infrastructure isn't like buying another disc for your PC. Plan your architecture and decide what you want out of it.
In surveying the market, look out for NAS interfaces - more and more equipment is likely to provide them in future.
Contacts
"How Much Information" by the University of California in Berkeley
Hewlett-Packard HP StorageWorks solutions
Fujitsu-Siemens network attached storage
Sun Microsystems http://uk.sun.com/consulting/networkstorage/ Network Storage Solutions
Procom www.procom.com/
NetFORCE 4000 Series - modular scalability to 32-TeraBytes
-IB-
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2. Battery backups: are you interruptible?
UPS: Upheavals Prevented Seamlessly
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It's so easy to buy another server and yet, suddenly, you've forgotten all about the other aspects - battery backup to name but one. Enter the Uninterruptible Power Supply (UPS).
How does a UPS work?
Connecting your valuable central server directly to the mains power is fine if your electricity supplier can guarantee never to have a power failure or a voltage spike, so we offset this eventuality by placing an Uninterruptible Power Supply (UPS) in the path between the mains power and your precious server. This UPS is 'charged' with the excessively tedious task of sensing the minutiae of mains voltage fluctuations 24 hours a day. When those fluctuations go beyond certain limits - say, more or less than 15 Volts above or below the UK's standard 240 Volts - the UPS strides in boldly with 2 measures :
- it supplies all the power needed from its internal battery, converting up from 12V to 240V via some fancy electronics;
- it communicates via UPS software with the server to initiate a clean shut down within a given time.
| UPS innards explained |
| A UPS basically contains a large transformer and a large battery. The transformer takes the voltage and steps it down (for charging) or steps it up (for backup) as required. The battery supplies all the server power needed ... but only for a certain length of time. How long is a combination of load and battery capacity. Bigger is better (and more expensive) but a smaller load (ie a smaller server) will also give a longer run time on backup.
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These 'emergencies', or spikes, can occur for tiny durations (milli-Seconds) and many times a day, if your local electricity supply is less than perfect.
The "given time" can be programmed beforehand by setting up UPS software, the most common being APC's PowerChute, and is typically set to around 5 minutes - enough leeway to avoid draining the battery too quickly while still allowing the server to 'down' itself gracefully. During this time the UPS will usually bleep continually (probably once a minute) to alert anyone in the vicinity that it's on standby power. It's only noteworthy in being the dullest ring tone you ever heard.
After the 5 minutes or so is up, the Uninterruptible Power Supply electronics 'talk' to the server telling it to start shutting down the server just as if someone were doing it from the console; not exactly a scintillating or elaborate conversation, so the plain old RS232 9-pin interface is fine for the job.
For the large part of its life, however, a UPS just sits there awaiting disaster and occasionally topping up its internal battery, ready to step in heroically.
Two's company, three's a farm
What happens when you buy a second or even a third server?
| Simple UPS battery backup for multiple servers |
| File server |
Mail server |
Database server |
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| UPS |
UPS |
UPS |
These scenarios are now common where you employ separate servers for, say, a database engine like Microsoft's SQL Server or a hardware-hungry dedicated mailserver like Exchange.
However, just plugging the extra server into the back of the single UPS immediately throws up 2 problems:
- The drain on the existing UPS will increase, in extreme cases, exhausting all the battery juice before any shutdown procedures commence; going from say, half load to full load can actually result in more than halving the run time of the UPS.
- With no communication to additional servers via an RS232 serial interface, 'shut down' will be equivalent to just losing the power, ie far from orderly and effectively no protection at all.
A UPS can actually connect between 2 to 7 devices (servers, external tape drives, etc), but the software only allows intelligent communication with a single device.
| Networked UPS battery backup for multiple servers |
| File server |
Mail server |
Database server |
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| UPS with Ethernet card |
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Thus in a 'server farm' setup, there are two alternatives, at the risk of falling into a pattern - both illustrated here :
- A separate UPS backs up each server
Hey - you are really covered for mains failures now! However, aside from the initial expense and space taken up by separate UPS units, the replacement of separate batteries (which don't last forever) will cost extra time in ordering and reinstallation.
- One UPS plus a network card
A single UPS containing a network card communicates with auxiliary servers and tells them to shut down via their respective network connections.
This latter is the best solution for a multi-server environment. The UPS contains an Ethernet Network Interface Card (NIC) - much like any net card fitted to a PC - and this is connected to the central Ethernet switch. All servers connected to the switch that have UPS-enabling software installed then communicate with the single UPS via the network and shutdown automatically and simultaneously if required.
Other equipment
Don't forget to backup relatively low power equipment like switches and hubs or your network will disappear very suddenly in the event of short outages of power (fractions of a second), even though the servers continue running quite happily.
What about PCs and workstations?
It's not impossible, but is fairly expensive, to provide a UPS for every workstation, indeed for home users and teleworkers, this is not an unreasonable cost for the protection it affords them. However, for those connected to a Local Area Network, dedicated battery backup per PC is over the top.
The act of shutting down a file server (so called 'downing') will normally close off all files in an orderly manner, ie those that have been saved so far. Any data in the memory (RAM) of an unprotected individual workstation will simply disappear along with mains power, but this loss is typically only 10 minutes worth of human work if you have enabled features like autosave that are available in many applications (Word, Excel, Outlook).
None of this should to be confused with Battery Backed Cache, a method which builds in redundancy to server components. The memorably-named BBC feature allows the cache memory to remain intact or protected in the event of power being cut to a server. When the server's power is restored, you find that a battery has been keeping safe the shortcuts, login scripts and whatever else resides in the machine's cache memory. This was new to servers toward the end of 2002, though will probably appear in PCs in the not too distant future.
Prepping for battery backup
If you are designing or having a Network Comms or server room refitted, our recommendation is to have the power supply to be set up as a different circuit - that is, a separate external electrical supply, well isolated from kettles and electric drills. Generally, a qualified electrician will install the new circuit and hard-wire the UPS into this dedicated source of mains power.
How big a UPS do you need?
Our standard model - the APC 1400 will allow you approximately 10 minutes at the full load of and 20-25 minutes at half load with a single typical server plugged into it.
Check that the serial COM port of your server actually works. We have seen old networks where the supposed battery backup was connected to a serial port that never worked!
Not all UPS units were always accompanied by the necessary software to tell the server to start the shutdown routine. Fortunately, these days any new UPS are supplied with appropriate software and the most popular, American Power Conversion Corp., provide links to download software for their PowerChute units on their web site.
How to make it happen
Call us to find get help determining your best battery-backup solution.
Contacts
-IB-
Acknowledgements: Nishal Rooplal, Zorina Baksh, Wayne Toolan
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3. Windows.NEXT: long haul for Longhorn
The next version of Windows was announced in May, but we'll have to wait a couple of years for it yet.
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Long haul
Speculations, leaks and rumblings about Microsoft's next operating system have been going on for years, but although beta versions for testers will appear in 2004, the final version isn't likely to appear in the commercial arena until 2005.
Initially referred to as "Longhorn", the system will no doubt metamorphose into "Windows 2005" or maybe "Windows XP2" when it hits the streets, unless naming fashions have changed again by then, but for the minute the system itself thinks it's called Windows 6.0.
Microsoft executives claimed Longhorn will herald a new era of graphics processing capability, at the Windows Hardware Engineering Conference (WinHEC) in New Orleans.
Less filing, better finding
Microsoft's developments in the database area have led to in a new WinFS (Windows Future Storage) file system. Although you might associate this terminology more with removals and warehousing, WinFS promises us niftier searching and storage of files on our networks and PCs and the key no doubt lies in efficient indexing, crucial to database speed. This replacement for NTFS and FAT32 - file systems used in previous Windows operating systems up to XP - displays its database suitability by being re-used in the next version of Microsoft's SQL Server database software, thus far codenamed "Yukon".
Side show
One of the most visible, and hence talked about, additions to the standard XP-like layout here is the Sidebar. The very term, which crops up in browsers like Netscape and Mozilla and Office XP/2003, has come to mean a floating, configurable pane where users can place what they need most often - a kind of Frequently Used Quicklinks, though this particular acronym probably won't be adopted by MS.
Inside the Sidebar, various "Tiles" can be placed including preset ones like a clock or virtual desktop manager, as well as personal ones like a Most Frequently Used (MFU) programs list, toolbars, and Internet searching.
My show
Indicative of the expected ramp up in PC performance and thus the ability to handle ever larger quantities of data, Longhorn builds XP's graphics viewing facilities in the "My Pictures & Video Library", but extends with comprehensive filtering allowing us to arrange pictures and movies by categories such as date, subject, type or notes.
A comparable Game Library handler reveals the desire to keep home users on board in this new release too.
Portable storage gets a big support boost by (optionally) having external USB storage devices automatically synchronise with PC or download picture content without being prompted. As might be expected, a means of configuring components relating to Windows Tablet PCs is bundled in Control Panel.
Customers can only cope with clients
Reeling under the deluge of upgrades emanating from Microsoft like Windows 2000 series, Windows XP, Office XP and Windows 2003), the software giant's customers are weary from upgrading servers in particular. Longhorn is thus client-only and doesn't ship as a server version.
However, it's not quite as trivial as just reconfiguring desktops throughout your organisation since Longhorn's new file system will require major changes on your file server, the latter to be implemented as a (presumably major) service pack.
Those of us happy with their Windows2000-throughout installations may well decide to just wait on upgrading to Windows 2003 Server (nee Windows.NET) and take the plunge on a complete Longhorn-plus-2003 package in 2005.
Contacts
-IB-
Acknowledgements: Michael Kanellos, John Lettice, Joe Wilcox, Paul Thurrot
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4. Finding applets in Windows
How do you like them applets?
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People are always losing the shortcuts to common programs. The Windows desktop is configurable after all, so unfortunately that means it's as easy to lose stuff as it is to install it.
Applets like Notepad, Calculator and Character Map are handy everyday utilities and we're suddenly lost without them.
| Applet |
Run this |
From |
| Explorer |
explorer.exe |
C:\WINNT\ |
| Notepad |
notepad.exe |
C:\WINNT\ |
| Character Map - for inserting accented characters |
charmap.exe |
C:\WINNT\SYSTEM32\ |
| Calculator |
calc.exe |
C:\WINNT\SYSTEM32\ |
| Disk Cleanup |
cleanmgr.exe |
C:\WINNT\SYSTEM32\ |
| Clipboard Viewer |
clipbrd.exe |
C:\WINNT\SYSTEM32\ |
| Command shell/window |
cmd.exe |
C:\WINNT\SYSTEM32\ |
| IPConfig - find your IP details |
ipconfig.exe |
C:\WINNT\SYSTEM32\ |
| Screen Magnifier (accessibility tool) |
magnify.exe |
C:\WINNT\SYSTEM32\ |
| Paintbrush |
mspaint.exe |
C:\WINNT\SYSTEM32\ |
| Narrator - speaks typed characters on screen (accessibility tool) |
narrator.exe |
C:\WINNT\SYSTEM32\ |
| On Screen Keyboard (accessibility tool) |
osk.exe |
C:\WINNT\SYSTEM32\ |
| Task Manager |
taskmgr.exe |
C:\WINNT\SYSTEM32\ |
| Wordpad |
wordpad.exe |
C:\Program Files\Windows NT\Accessories\ |
| NetMeeting |
conf.exe |
C:\Program Files\NetMeeting\ |
Make it happen
To test you have rediscovered the right applet, you can get to it through the start menu:
| Start | Run | (type the path and command from the table)
These examples are for Windows 2000 but simply running a search for *.exe files in other operating systems (Win98/XP) will point you to some of the most obvious applets. (NB Not all of these will perform visible functions. If you're new to the programs that show up in your search, a broad gauge of whether they are useful is to stick to the ones with brightly coloured icons).
It's easy to put the shortcuts back on the desktop too.
With your right mouse button, drag one on to the desktop and select "Create Shortcut(s) Here".
Done!
(Loosely) related articles
How do you like them apples? Where it originated
-IB-
Acknowledgements: Ken Flury
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5. Teleworking gets new legal backing
Flexi-time comes home for parents
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At the start of this financial year, a new employment law, The Flexible Working (Procedural Requirements) Regulations 2002 gave employees with children under age six a right to request flexible working. The means some three and half million parents will be eligible to apply.
Although the employer is only required to consider the request, rather than be obliged to execute it, s/he must state reasons for any refusal in writing.
| Avaya calculated savings of over £3,500 per worker per year |
At least one company jumped the gun on the 6th April deadline. Telecommunications company Avaya brought their virtual private networks (VPNs) into force to allow employees to access corporate information remotely, yet securely, saving around £690,000 globally on telecom costs per annum. Their 2002 trial calculated savings of over £3,500 per worker per year from using VPN technology.
They employed measures such as:
- Unified ‘find me’ messaging applications to ensure employees can pick up all messages (email, phone and fax) and work effectively from outside the office
- Phone calls can be made via a PDA or PC using IP telephony with Avaya’s IP Softphone to reduce call costs by routing calls made from any location over the corporate network as opposed to the public network
- Wireless Access Points (APs) and wireless cards to allow flexible workers to hot-desk quickly within the office without being connected by wires to the network
| Flexible working (aka "contract variation") must be written down, showing the variation agreed to and the effective date |
Developing a policy
Avaya went on further, however, to develop a flexible working Human Resources policy for all of its UK employees - 900 of them - not just those with young children. Technically this means a subsidised broadband connection and a one-off contribution towards office equipment for each flexible worker, but also a different approach.
Audrey Campbell, Services Implementation manager, EMEA saving four hours travelling every day while still managing a Europe-wide team of 120 when she is not travelling in countries such as France and Germany – all this solely from her home office in Bedfordshire.
Mike Young, HR Director for Avaya across the UK, Ireland and the Nordics sums up the approach: "Both businesses and employees can benefit from flexible working. However, to make it work successfully it needs to be undertaken in an environment of trust with an agreed structure and framework. Organisations need to move on from the ‘80s mentality where managers felt employees weren’t working if they couldn’t see them."
Are you ready?
DTI research at the end of 2002 indicated that flexible working was a prime benefit sought by 46% of job hunters comparing with 56% of employers who have never considered flexible working schemes.
How to make it happen
Contact us about setting up virtual private networking (VPN).
Contacts
The Flexible Working (Procedural Requirements) Regulations 2002
Order copies of the Regulations here
Guidance for employers and employees: http://www.dti.gov.uk/er/flexible.htm
Explanation of legal implications
Rights on Leave, Pay, Time off regarding Maternity, Paternity, Flexible Working, Parents, Adoption and Dependants: http://www.dti.gov.uk/er/workingparents.htm
Avaya offers flexible working opportunity ahead of new Employment Act
Kitting out Teleworkers
Homework becomes popular!
Cut IT support costs with hot desking
-IB-
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6. Blacklisted! Email and blocking lists
Attempts to block spam can result in 'throwing the baby out with the bath water'.
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Blockage on the line
Any of you sending out emails to a list of addresses you keep - like newsletters to members or press releases - may find increasingly that your messages are returned with a notice saying you have been blocked. These Delivery Reports are the result of your recipients attempting to block spam or unsolicited commercial email (UCE).
The good news
Analysing the returns, you can see they often show that your organisation is not at fault - it's your ISP that has been blacklisted.
The Bad News
There's not a lot you can do about it, other than change ISP.
How it looks in practice
| Examples of blacklisted mail servers |
| Example 1 |
Your message was not delivered to: recipient1@tabloidPaper.net
for the following reason: Diagnostic was Unable to transfer, -1
Information MTA 'tabloidPaper.net' gives error message
http://dsbl.org/listing?ip=193.xxx.xxx.xxx; mail from 193.xxx.xxx.xxx rejected:
administrative prohibition (host is blacklisted)
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| Example 1 |
Your message was not delivered to:
recipient1@broadsheetPaper.co.uk for the following reason:
Diagnostic was Unable to transfer, -1
Information MTA 'broadsheetPaper.co.uk' gives error message Denied by policy:
Sender is listed on DNS-based RBL
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In these cases (see panel), both the mail transfer agents (MTAs) or mailservers at tabloidPaper.net and broadsheetPaper.co.uk are telling us they use Real time Blocking Lists (RBLs) - also known as Blacklists or Boycott Lists - and are reporting that the one of the servers your organisation uses for transferring email (eg largeisp.com) is on one or more blocking lists - a list of mailservers from which spam is known to emanate.
List mania
Such lists contain the IP addresses of servers that constitute an open relay, an open proxy or has another vulnerability that allows anybody to deliver email to anywhere, through that server. Other lists show known spammers and the information may be free or available via subscription.
Large companies in particular 'plug-in' to these sources of information because they provide a relatively easy solution to preventing the influx of unwanted mail, tying up both their Internet bandwidth and employees' time dredging through the stuff.
Unfortunately it is common for very large providers like BT, AOL and Yahoo! to be abused simply because
spammers, like anyone else, find it easy to set up accounts with them, usually for free. It's a difficult and never-ending task for these big ISPs to shut down all of their spam-producing accounts, but nevertheless it's in their interests. Periodically they will be added or removed from RBLs depending on the degree of abuse their servers cause and the annoyance suffered.
| Typical responses indicating fly-by-night spammers |
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"User unknown in local recipient table"
"Non existent host/domain (NXDOMAIN)"
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The question for administrators of any network is whether they want to continue to accept their blocking feeds from the people who run those lists, because clearly there comes a time when they are 'throwing the baby out with the bathwater'. There will always be large ISPs and inevitably they will hold accounts for both 'goodies' and 'baddies' in the email world, so you may consider that blocking on the basis of an entire ISP's domain may not be a good idea.
DIY blocking
Running your own blocking list in-house is a possibility if your mailserver supports it. Adding prolific spammers' addresses ASAP and then removing them in a month or so prevents a good deal of the unwanted mail but keeps the list small, because spammers often create accounts for once-off use. It's also quick and easy to correct any mistakes where genuine senders are blocked, unlike RBLs run by a 'committee'.
Conclusion
With any blocking system, the recipient organisation has to decide how much mail to reject and how much effort they are prepared spend on the system's accuracy - it's not a simple answer.
A list of lists
Related articles
Will email become unusable? IB February 2003. Tips on preventing spam
"Your privacy on the line" IB November 2002
A simple way to combat spam via secondary Webmail, IB March 2002
Change your diet - prevent spam IB October 2002
Opt-in only E-Privacy directive
-IB-
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7. Return-To-Sender: Email bounce-backs
Somebody's mailserver is trying to tell you there's a delivery problem, but what does it mean?
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You spend hours crafting that electronic newsletter for your membership or a carefully-worded press release to attract the maximum journo impact. All you have to do is click "SEND" ....
but, horror of horrors, your mailbox suddenly starts to fill with failure messages couched in mailserver speak!
Is it all broken? Will you have to resort to fax?
Don't panic!
Unlike postal addresses and, to a lesser extent fax, email addressing is volatile. It's dead easy to switch emails, compared to bringing a new fax number on line or changing your location!
If people can change email addresses you can be sure they will. Old accounts collect too much spam, or perhaps new premium charges are applied, forcing owners to move, and in organisations people move on to new positions or leave altogether.
Although these changes may not happen frequently, your distribution list is particularly sensitive to this 'churn', which may be as much as 5% per month - 50 addresses in every 1000.
So the first thing to note is that these return-to-sender notices are normal and probably more prolific than you expect.
What exactly is a bounce-back message?
It's an automated message saying your recipient can't be found.
Any email message quoting something like "delivery failure" in its subject line is usually from a Mailserver - typically the one where your recipient's mailbox is supposed to reside.
The routing shown here is broadly how you communicate with other people and their mailboxes.
| Typical mail routing |
| Your Mailboxes |
| | |
| Your Mailserver |
| | |
| Your ISP |
| | |
| Remote ISP |
| | |
| Remote Mailserver |
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| Their Mailboxes |
These are roughly the types of errors you get, in order of probability:
- Address was misspelled or wrongly guessed: The most common cause. Check your address book, distribution list, database, whatever.
- Person has left: Their email account has been closed. Find out who you are supposed to correspond with at the remote organisation. In desperation, you can always write to the postmaster@ address to get this information.
- Remote Mailserver has failed: Mailservers give up or go offline temporarily more often than you might suspect. If the remote mailserver or ISP has 'gone down', then you may get a message immediately, depending on how temporary the failure is.
Check the domain part of the email address you sent to.
- Returned mail: Cannot send message within 5 days: If it's more serious (no mailserver, no domain, no nameserver entry found), you may get an email every 24 hours saying it's still being tried; often you receive progress messages saying you don't need to send your email again. After 5 days though, it gives up altogether - even mailservers aren't relentlessly stupid.
Either your recipient's IT infrastructure is in severe trouble or the organisation's gone bust. There's no way you are going to get an email to them speedily, try another form of communication.
Easing the flow
- For your distribution list, try to collect aliased emails for organisations, like pressdesk@ or newsletters@ - they are more durable.
- Stream your bounce-backs and replies to a separate folder with filtering rules, for each outgoing missive. You must set these rule up beforehand, but they can trigger on your specific subject line or say, the words "delivery failure". This way you can analyse replies all together, rather than having them jumbled up with your everyday mail.
Related articles
Create embargoed press releases by delaying email delivery
Is your email system down?
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8. Clicks of the Trade
--- Quick tips for happier clicks! ---
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More help at hand. All the back issues just a click away
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Set your PC right
Sort out all those niggling pound signs and keyboard options in one go and leave 'typing hell' behind you!
Go Start | Settings | Control Panel
- Then click the "Keyboard" (also Input locales on Windows 2000)
- Set "English United Kingdom" as the primary language and ensure its properties define the correct keyboard layout, again typically "UK".
On Windows 2000 upwards you can set a particular key to switch between languages
Go Start | Settings | Control Panel
- Then click the "Regional Options" icon
- The General tab is where you set your location.
- Set each of the Numbers, Time, Currency, Date tabs to the values you want.
** try it now **
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