[lug] Email brokenness?

[D. Stimits]

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 the heck is that supposed to mean, and what do I do about it?

I remember a while back when I couldn't send email to you and DNS 
claimed your domain didn't exist. Currently if I use "host 
syntacticsugar.org" it does nothing at all...it doesn't say you don't 
exist...it simply returns without anything at all. A newline. Perhaps it 
is in the dns of comcast and not your end. Or...perhaps your domain is 
not being properly propagated (e.g., maybe ECN is enabled and there is a 
broken router between). Perhaps you have something that isn't supposed 
to respond with an IP address and is only for email, which would explain 
the lack of response. I suggest you call their tech support at comcast 
and ask them to explain. Their toll free number: 1-888-262-6300.

D. Stimits, stimits AT comcast DOT net