Ruleset questions

Hugo van der Kooij hvdkooij at
Thu Aug 14 05:41:35 IST 2008

Hash: SHA1

Richard Frovarp wrote:
| Glenn Steen wrote:
|> 2008/8/14 Richard Frovarp <Richard.Frovarp at>:
|>> How would one go about blacklisting a From email address that is did not
|>> come from a subnet. Email would for this one address would only come
|>> legitimately from one of my subnets. Everything else should be thrown
|>> away.
|>> What would be the best way to accomplish this?
|>> Thanks,
|>> Richard
|> Apart from SPF, which I'm sure one could use to reject fakers, one
|> could do as I do in postfix... I simply reject all faked senders (we
|> only allow internal senders for our domain, exactly as you would
|> likedo it)... A simple access map restriction on the sender...
|> something like "smtpd_sender_restrictions
|> permit_mynetworks,check_access regexp:/path/to/accessfile ... How one
|> would do it with other MTAs... I do not know... Should be possible
|> though:-).
|> Cheers
| SPF wouldn't do it. SPF would only check the envelope from. We are
| concerned about the displayed from. And in particular of only one of our
| accounts.
| We run sendmail. However, how does your system handle mail from other
| systems claiming to be from your users? Like say this mailing list?

First off. Only Microsoft made the error to rely on the From: line above
~ the SMTP sender in their interpretation of SPF.

Check the SA rules as there are some rules there that check if Yahoo
users originate from Yahoo and do not falsify the From: line.

You could use those to learn how to do it yourself.


- --
hvdkooij at     

	A: Yes.
	>Q: Are you sure?
	>>A: Because it reverses the logical flow of conversation.
	>>>Q: Why is top posting frowned upon?

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