Postfix/Exim sender address rewriting (was: Postfix ... ComCast port 587)

[Bill McGonigle]

On 2009-01-21 1:06 PM, Ben Scott wrote:
>    The scenario here (for me, and the OP) is rewriting email addresses,
> not masquerading as a different host.:)

Righto, and certainly you can do that with address rewriting, but why 
not setup the MUA properly in the first place?  I understand your edge 
case about gmail but I think you can consider yourself fortunately 
unique in that scenario. :)  On the broader topic of getting mail 
through, though, you need to use real hostnames when speaking SMTP on 
the Internet.

Comcast can't reject all mail with a From: other than comcast.net or 
doing round-trip DNS lookups as they'd break 77.6% of their SOHO users' 
e-mail.  They're doing the right thing by rejecting fake mail From:'s, 
lots of spammers do that.

I'll sometimes also reject mail with bogus Received: headers so using a 
valid hostname is important there too.  And I do reject bogus HELO's, 
which drops my spam by about 35%.

FWIW, my home mail goes over a Comcast connection, but I run my own TLS 
MTA for my MUA's to talk to as we have several reasons not to trust Comcast.

-Bill

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