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From: zzflop on 10 Mar 2010 12:29
I have recently ran into a problem with being blacklisted by some
mail severs spam controls. I have used the same setup for some years
now; local mail server sending
through my isp via smarthost and retrieving mail with fetchmail.

I set up sendmail to use an isp smarthost using the guidelines from
sendmail.org.When
this account was opened with embarq , now century link, I did an
online help with one
service reps and asked about using sendmail with their service and
was told that it would
be fine as long as I used port 587 for submission.

I didn't actually use the submission port at first because of a
misunderstanding on my part.
A netstat showed that port 587 was open, and I didn' t realize that
this was a listening port
for my sendmail and that I needed addition sendmail.mc configuration
to submit to port 587
on their server. I don't think this was relevent to the current issue
as they accepted and
and relayed my mail on port 25 anyway.

When I try to send mail to my sister through verzion, it bounces with
the message that because
of spam controls on their server mail from this ip ( the one assigned
to my router) is not accepted.

What I don't understand is why they are seeing the ip as the origin .
Isn't that the point of using
your isp as smarthost , so that reverse dns resolves to a real domain.

This is an annoying problem; to be blocked by spam controls when
trying to send legitimate
mail. Any observations or tips are appreciated.

Mike H.

From: Ole Hansen on 10 Mar 2010 21:07
On 10-Mar-10 12:29, zzflop wrote:
>
> What I don't understand is why they are seeing the ip as the origin .
> Isn't that the point of using
> your isp as smarthost , so that reverse dns resolves to a real domain.
>

Yes, it is.

Maybe you aren't sending through your ISP's outbound server after all?
Or not via port 587?

Send mail from your sendmail setup to one or more different email
account of yours, for example your gmail account, and check the headers.
Pay careful attention to the "Received:" headers to verify the path
your mail takes. Also, double-check all your assumptions. Are you really
connection to port 587 for outbound mail (tcpdump it)? Are you
authenticating to the smarthost? (change password to something incorrect
and see if you can still send) Etc. etc.

Good luck,

Ole


From: zzflop on 11 Mar 2010 14:51
On Mar 10, 6:07 pm, Ole Hansen <ole.at.redvw....(a)foo.net> wrote:
> On 10-Mar-10 12:29, zzflop wrote:
>
>
>
> > What I don't understand is why they are seeing the ip as the origin .
> > Isn't that the point of using
> > your isp as smarthost , so that reverse dns resolves to a real domain.
>
> Yes, it is.
>
> Maybe you aren't sending through your ISP's outbound server after all?
> Or not via port 587?
>
> Send mail from your sendmail setup to one or more different email
> account of yours, for example your gmail account, and check the headers.
>  Pay careful attention to the "Received:" headers to verify the path
> your mail takes. Also, double-check all your assumptions. Are you really
> connection to port 587 for outbound mail (tcpdump it)? Are you
> authenticating to the smarthost? (change password to something incorrect
> and see if you can still send) Etc. etc.
>
> Good luck,
>
> Ole

The above checks revealed that I was not using 587 , the headers
pointed to the wrong place and that I was not really authenticating to
the isp's server.

Checking sendmail.mc closely I found a missing backtick in the
define(`RELAY_MAILER_ARGS', `TCP $h 587')dnl
statement and I had some LOCAL_NET_CONFIG statements that were
holdovers from a different setup. I "assumed"
that they would't hurt anything but was dead wrong there.

Commenting the statements and fixing the backtick put everything back
in order. Thanks for pointing me in the right direction. I won't
forget to double-check my assumptions in the future.

"Your reasoning is excellent - it's only your basic assumptions that
are wrong." . . . Ashleigh

Thanks again.

Mike H.
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