ah, that crack. ok, now I remember from a long time ago that attempt to crack the MTA with excessively long SMTP command.This is the length of a single command such as HELO xxxxxxxxxxxxxxx ... being more than 512 or 2048 characters.
So IMGat was passing these longs SMTP commands through to IMail and got caught.
hmm, in my latest IMGate config, I have :
header_size_limit = 1024
so any msg through IMGate exceeding 1024 would be blocked. I'm even thinking of dropping that to 512 or lower, since 99.99% of valid mail doesn't put that many addresses in the, eg, the cc: field. and 99.99% that do it are spam.
It's a simple limit, no coding required.I don't know the exact details except that a blast of E-mail address harvesting won't trigger it. It's possible that a blast of real messages will trigger it. It's not clearly documented and it might be just as well - it makes it easier for spammers to code around it.
http://support.ipswitch.com/kb/IM-19980413-DP01.htm
So I'll put IMGate config to 512 max. and that's RFC max, not RFC minimum.
maybe 256 would be enough to allow all Received: headers? looks like it. 256 is nearly 4 lines of 70 characters.
hmm, maybe 128 would be enough?? :))
Len
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