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Re: greylisting done at end of headers, or end of daya (QUIT) ?

2007-01-30 17:21:23

william(at) wrote:
Who exactly generates new Message-ID per each transmission???

There are legitimate mailing list / bulk mail applications in use by Fortune 500 companies that only keep a message template on disk. It's the only way to build an application capable of running on a single machine and sending personalized versions of a single E-mail to tens of millions of people. All the "variable" information, like the recipient's name, E-mail address, date, and the Message-ID field, are added on the fly while streaming the message to the SMTP receiver. If the message gets a 4xx on the first try, the MTA logs the attempt but throws away everything else; so indeed the Message-ID changes on each attempt.

No, I don't remember which applications did this, just that I saw it a lot at Habeas. And yes, it does play merry hell with duplicate detection (and on message tracking -- the Message-ID field is nearly useless).