Splitting a multiple recipient message into individual messages

[Drew Marshall]

On Thu, July 6, 2006 09:46, Jim Holland wrote:
> Hi
>
> On Sat, 27 May 2006, Stephen Swaney wrote:
>
>> I finally found a few minutes so this has been added to the Wiki:
>>
>> http://wiki.mailscanner.info/doku.php?id=maq:index#sendmail_8.13_anti-spam_/
>> _denial_of_service_protection_features
>>
>> I've also added:
>>
>> "How Split a Multiple Recipient Message in Single Messages" under:
>>
>> http://wiki.mailscanner.info/doku.php?id=maq:index#misc._questions
>>
>> I've added the sendmail instructions. If anyone wants to add the Exim
>> method
>> to split messages to multiple recipients into individual messages please
>> feel free :)
>
> Thanks for these notes.  I see the comment that this may increase the load
> significantly on the server as it will have to process more messages.  I
> would also imagine that it would have a significant impact on bandwidth as
> well, as each recipient's copy of a message would be delivered separately.
> That is of much more significance for ourselves than the CPU load as we
> are handling traffic for 2500 people on a 64k leased line.  On the other
> hand we handle large mailing lists that could involve sending outgoing
> mail to over 2000 people, and these lists would collapse if we were to
> send each message individually.  What we need therefore is a way of
> splitting incoming messages (where the bandwidth issue would not arise
> but where we need to be able to apply rulesets individually) but not
> outgoing (where we need to conserve bandwidth and where rulesets generally
> don't apply).  Do you know how to modify the sendmail local ruleset
> accordingly?

<Caveat> I am not a Sendmail expert or user </Caveat>

I wouldn't think this is achievable as Sendmail won't know what was the
original message once it is split as all the split messages will look like
new individual queue files. However, all shouldn't be lost as sendmail
should [be capable of] make one SMTP connection and send as much mail as
permitted (By the receiving and sending MTAs) in one connection so saving
the bandwidth of individual SMTP sessions. Obviously this doesn't replace
the sending of one message with multple recipients but it would help.

Perhaps there is another angle where by Sendmail only splits messages of a
certain size? Most Spam is not large so you only really need to scan say
under 750Kb (Or may be even less) and you could split these with different
rulesets but it also depends on what you apply rulesets to Spam, virus
scanning, attachments etc as to whether this idea would work.

Drew


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