How to detect forged From and Reply-to addresses from your own domain

Alex Neuman alex at
Mon Mar 8 17:48:08 GMT 2010

They'd better not be or they'll stand to lose a lot of business. Unless you're being silly enough to run an unauthenticated smtp server on 587, there's no reason to block it. If you know you can use 587, you usually know enough to set it up as an "authenticated *only*" server and not a regular "send me whatever and I'll deal with it" smtp server like you usually get on port 25's.

On Mar 8, 2010, at 12:17 PM, Michael Masse wrote:

> I've heard of ISP's doing this with port 25, but not 587 which is a standard alternative port for smtp submittal.  Are there ISP's redirecting 587 as well?

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