UKTC Archive

UPDATE: More on the UKTC system changes - bounce handling

Subject: UPDATE: More on the UKTC system changes - bounce handling
From: UKTC List Admin
Date: Dec 27 2001 16:28:00
   Bounce handling
   Digests - some problems
   The new archive - notes and tips

This is the first of several update posts concerning the recent changes to 
UKTC. The way in which bounced (undelivered) messages are dealt with under 
new system is outlined, along with a note about digest delivery and the new 

On 12 December 2001 I announced that plans to move the UKTC onto a new 
using different software had been brought forward and implemented in a hurry 
due to the rapidly worsening state of the old machine.

That announcement itself was sent out in a hurry and as a result did not 
all the consequences of the recent changes. As I don't have time to compose 
all embracing document on the changes at present I'll be posting information 
dribs and drabs with a subject line beginning "UPDATE:"

The UKTC handles an average of over 50 messages per week for over 250 
subscribers - over 12500 message deliveries each week. The vagaries of the 
Internet inevitably mean that not all of those messages reach their 
destination. Those that don't are 'bounced' - returned to the sender. In a 
mailing list context the sender is not the original author of the message, 
the list's administrator.

Many mailing lists automatically delete subscribers whose messages are 
returned. The assumption is that the address is no longer valid and it is 
therefore pointless to continue sending messages to it.

Until the recent changes I had chosen to be somewhat forgiving about messages 
that didn't reach their desination and were bounced back to me, painstakingly 
reading through them and noting persistant offenders. Occasionally I've 
manually removed subscribers if mail has carried on bouncing and looks as if 
is a problem that won't be resolved, using the kind of fairly fuzzy criteria 
that humans are much better at assessing than computers.

The amount of work involved in this has grown considerably as the UKTC has 
grown. Accordingly I have now decided to make use of features for automating 
the handling of bounces.

Subscribers whose messages bounce will now be removed from the list 
automatically. Removal will not take place at the first bounce - if it did, 
everyone working for a local authority, together with all users of lineone, 
yahoo, hotmail, appleonline and freeserve would have been removed by now!

Instead, thresholds have been set which I hope will ensure that subscribers 
experiencing temporary mail problems will not be unduly kicked off, whilst 
addresses that really have had it will go. At present the thresholds are 20 
fatal or 50 transient bounces in any 10 day period.

Should you find yourself unexpectadly unsubscribed this is likely to be the 
reason why. An attempt will be made to notify anyone who is unsubscribed in 
this way, but naturally this is unlikely to succeed since the reason for the 
action is that their mail is not getting through.

There are certain people who may be more affected by this than others. The 
main groups that come to mind are:

  * Those who have a quota on their mail account. If you don't check your 
    for a while (perhaps because you're on holiday) and go over quota new 
    for you will be refused. This will result in bounces being generated.  
    Different systems differ in the type of bounce generated for over quota 
    accounts - some use transient codes whilst others use permanant ones. If 
    are going on holiday you should consider marking your UKTC subscription as
    'VACATION' using the accoung management facilities at

  * Those using work email accounts where particular corporate security 
    policies exists about attachments. A number of local authorities are 
    included here. These authorities quarantine attachments but send a message
    to the return address of the mail envelope advising the sender that the 
    message has been quarantined. These messages are likely to interprated as 
    bounces. Whilst it is very rare for 20 attachments to be sent to the UKTC
    in 10 days, it's not impossible and if you work for such an employer you 
    should bare this possibility in mind if your subscription suddenly stops.

Digest readers may have noticed that arrival of digests is rather sporadic at 
the moment. This is due to an odd problem affecting the UKTC whereby certain 
scheduled tasks are not happening. 

I am looking into this, but in the mean time I have implemented a work 
Digests are currently being generated whenever a new message is sent to the 
UKTC and more than 24 hours have elapsed since the last digest was sent.

It is hoped to be able to return to daily digest mailing at a set time as 
as possible.

The following are a few notes on the new archive available at

The archive now covers all the messages that have been sent through the UKTC 
the three years since it's inception - that's around 6000 messages. In order 
make the whole thing a bit more manageable it has been broken down into one 
year segments.

For each year four indexes are available - by thread (the default), date, 
author and subject. The first two of these are ordered with the most recent 
message first.

From any given message you can move to that message's position in any of the 
four indexes for the year by clicking the appropriate link in that message. 
This is a slightly slow process as the correct position has to be calculated 
the fly. By this means once you've found one message from Mr X you can find 
the other messages from that year by the same Mr X by clicking on the 
link 'Author Index'.

There is also a dedicated archive search facility. The archive front page has 
form to access this, or you can find one in the dark blue navigation bar down 
the right of any archive page.

The archive lags slightly behind the list. In order to avoid overloading 
messages are not added as they arrive. Instead, the archive is updated every 
minutes. The search index is updated every night in the small hours, UK time.

Chris Hastie
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