Re: flushing mail: obstacles

Glynn Clements (glynn@sensei.co.uk)
Thu, 22 Apr 1999 10:48:55 +0200 (GMT--1:00)


Alexy Khrabrov wrote:

> ----- Transcript of session follows -----
> ... while talking to unagi.cis.upenn.edu.:
> >>> MAIL From:<root@yaw.suffix.com> SIZE=115
> <<< 451 <root@yaw.suffix.com>... Domain must
> resolve
> khrabrov@unagi.cis.upenn.edu... Deferred: 451
> <root@yaw.suffix.com>... Domain must resolve
> Warning: message still undelivered after 4 hours
> Will keep trying until message is 5 days old

> Why does sendmail try to resolve yaw.suffix.com?

It's an anti-spam measure (rejecting messages where the sender's
address is clearly invalid).

You can disable this check with

FEATURE(accept_unresolvable_domains)

> I own suffix.com, but don't have a static IP for
> yaw, my local box, which I connect via ATT ppp.
> Since yaw.suffix.com It doesn't exist anyways, the
> return mail must come to braver@pobox.com -- but
> when I say
>
> sendmail -fbraver@pobox.com -q
>
> to flush the queue with that "from" fake, I get
> this:
>
> The original message was received at Wed, 21 Apr
> 1999 02:50:48 -0400
> from root@localhost
>
> ----- The following addresses had transient
> non-fatal errors -----
> khrabrov@unagi.cis.upenn.edu
>
> ----- Transcript of session follows -----
> 451
> khrabrov@unagi.cis.upenn.edu...
> unagi.cis.upenn.edu: Name server timeout
> Warning: message still undelivered after 4 hours
> Will keep trying until message is 5 days old

This is a DNS failure. I can resolve unagi.cis.upenn.edu OK, so check
your DNS configuration.

> Now I read Linux Mail-HOWTO and it bluntly says
> sendmail is obsolete and insecure, qmail
> (www.qmail.org) is the king of the hill.

It seems that someone is using the howto to promote their personal
bias as if it were fact.

Try running an `nslookup -q=mx ...' on some large technology
companies, then telnetting to the SMTP port on their mail servers. A
brief sample found most (Netscape, AOL, IBM, Digital) using sendmail,
one (Microsoft) using Exchange, and none running qmail. I guess that
these companies just aren't sufficiently computer literate to `know'
that qmail is where it's at.

-- 
Glynn Clements <glynn@sensei.co.uk>

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