[lug] Email brokenness?

[Lee Woodworth]

Chris wrote:
> Hi, everyone.
> 
> I've been having a really annoying time sending mail to users of
> comcast and yahoo, and I suspect it's some antispam trick that relies
> on something set differently from how it is.
> 
> I pull my mail to my desktop, and when sending mail, my client ssh's
> to my mail server and sends it from there so that it appears to be
> coming from the mail server rather than my desktop.  Anybody doing a
> reverse lookup on my domain and checking the source IP should not find
> any discrepancies.
> 
> Meanwhile, I'm getting errors like these when sending to users on
> comcast.  Postfix on my mail server is failing, with this error:
> 
> <username at comcast.net>: host gateway-s.comcast.net[204.127.202.26] said: 550
>     [PERMFAIL] comcast.net requires valid sender domain
What helo name is your mailer sending? It can be different than what 
your IP resolves to (check the myhostname, mydomain directives). An 
example of this I often see from M$ servers is the HELO/EHLO is the 
internal machine name (e.g. xxxx.LLC vs. xxxx.com). These people 
probably don't know they are publishing their internal AD domain name.

If you are still having problems, send me a message and I can look at 
what your server is sending out. My server is picky about the FQDN in 
the HELO, RCPT and MAIL commands, so it may be a useful test.

BTW, From my server, requests to your DNS server time out on the first 
try. A second try gets a response. Did you know you are publishing a 
LAT/LON for your machine name?

> 
> What the heck is that supposed to mean, and what do I do about it?
> 
> --
>     Chris Riddoch
> epistemological humility
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