[CentOS] Sendmail problem

Wed Apr 12 11:05:46 UTC 2006
Alexander Dalloz <ad+lists at uni-x.org>

Am Mi, den 12.04.2006 schrieb Thomas E Dukes um 2:23:

> Here'sanother bounce email:
> The original message was received at Tue, 11 Apr 2006 19:16:44 -0400 from
> localhost.localdomain []
>    ----- The following addresses had permanent fatal errors -----
> <xxxxxx at comcast.net>
>     (reason: 521-EHLO/HELO from sender does not map to
> localhost.localdomain in DNS)
>    ----- Transcript of session follows ----- ... while talking to
> gateway-s.comcast.net.:
> >>> MAIL From:<apache at localhost.localdomain> SIZE=2176
> <<< 521-EHLO/HELO from sender does not map to
> localhost.localdomain in DNS <<< 521-sending machine name must be provided
> as a fully <<< 521-qualified domain via EHLO/HELO command.
> <<< 521-see section and 4.1.4 of RFC 2821 <<< 521 521: Comcast
> requires that all mail servers must have a PTR record with a valid Reverse
> DNS entry. Currently your mailserver does not fill that requirement. For
> more information, refer to:
> http://www.comcast.net/help/faq/index.jsp?faq=Email118405
> 554 5.0.0 Service unavailable

2 things:

1) Your mail host at that time of the mail had the hostname
localhost.localdomain, thus your Sendmail used it for EHLO/HELO. You
fixed that meanwhile

2) The remote side requires not only a valid forward DNS record
(palmettodomains.com points to that IP) but too a matching reverse one.
From here I can't judge whether the named IP is static and thus assigned
by your ISP. If that is the case then you really should take care for
both types of DNS entries. If not (you are on an dynamic line) you
should use your ISP's mail host as SMART_HOST within your Sendmail
configuration. DynDNS is a very bad base for reliable mail services.


Alexander Dalloz | Enger, Germany | GPG http://pgp.mit.edu 0xB366A773
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