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@tucows.com