North American Network Operators Group

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Re: SMTP spoofing ?

  • From: Perry E. Metzger
  • Date: Thu Feb 19 13:03:05 1998

John R Levine writes:
> Are there any routers currently available that can do port 25 spoofing for
> dialup users?  That is, when the user attempts to connect to port 25
> anywhere, he in fact connects to port 25 on your own SMTP server instead. 
> In case it's not obvious, it's for spam management.

It seems simple enough to block all outgoing SMTP to anything but your
own server, and to apply such a filter on your dialups. I don't know
if the more complex solution you propose is worth it -- the users will
quickly learn where they should aim their mail...