Large Mail Provider Throttling

Edward Gray egray at tucows.com
Thu Jan 22 23:07:19 UTC 2004


As probably many of you have already experienced, we have been hit
with mailbombs with forged Hotmail (or other large provider) addresses
recently.

This has resulted in the large provider throttling our mail flow which
forces messages to be placed into our local queue for retry at a later
time. This ultimately has resulted in our customers reporting delays
in emailing such large providers (ie. Hotmail).

To protect ourselves from delayed mail, we have implemented several
system wide rules to block Autoreplies and Undeliverable messages from
being sent to the large providers. Unfortunately, this has resulted in
many complaints from customers (since it's all or nothing). We have so
far, left these rules enabled 24x7 since, the system already becomes
degraded by the time we realize an event is occurring.

I was interested to see what other techniques or steps people have
taken to protect themselves from these types of threats and whether
they have managed to handle a large #of accounts without preventing
AutoReplies and Undeliverable messages to large providers.

For instance, has anyone been able to approach such large providers
and request special handling of mail coming from their system (higher
throttling threshold for example)?

Thanks in advance,

Edward Gray
Director, Operations & Networks
Tucows.com Co.
egray at tucows.com




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