[CentOS] sendmail delay in presenting banner

[Bart Schaefer]

This is probably being caused by DNS timeout trying to reverse-lookup
the connecting IP.  Check that your resolver (/etc/resolv.conf) is set
correctly and responding to e.g. "dig -x [IP-address]" queries in a
timely manner.  If you are using DHCP, note that /etc/resolv.conf may
be automatically created by the network setup scripts so manual edits
may not "stick".

On Sun, Mar 23, 2014 at 8:39 AM, Gregory P. Ennis <PoMec at pomec.net> wrote:
> I am using a Centos 6.5 machine as a mail server with sendmail as the
> MTA.  I have a problem with a delay of sendmail presenting its banner so
> that the process of accepting e-mail can begin.  The log files
> demonstrate as much as a 2 minute delay between the connection and the
> banner presentation.
>
> #telnet Mail.DOMAIN.com 25
> Connected to mail.
> Escape character is '^]'.
> < two minute delay before the next line is presented>
>  h220 Mail.DOMAIN.com. ESMTP Sendmail 8.14.4/8.14.4; Sun, 23 Mar 2014
> 10:17:44 -0500
>
> Log entries on the mail server for the above connection:
> Mar 23 10:16:05 Mail sendmail[31229]: NOQUEUE: connect from
> NAME.DOMAIN.com [10.0.0.187]
> Mar 23 10:17:44 Mail sendmail[31229]: AUTH: available mech=GSSAPI
> CRAM-MD5 DIGEST-MD5, allowed mech=EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5
> LOGIN PLAIN
>
> I have made the observation that if I put in the following line in the
> access file the 2 min delay goes away
>
> Connect:10.0.0.187                          RELAY
>
> Obviously I can not set up a relay for every ip address, but this does
> solve the problem for internal network delivery of mail to the mail
> server.
>
> I am using named for local dns service and have not been able to
> identify any errors or problems.
>
> When I evaluate
>
> nslookup NAME.DOMAIN.com 127.0.0.1  I appropriately get 10.0.0.187
>
> So far I am stumped on this problem, if any of you have suggestions I
> would appreciate your help
>
>  Greg Ennis
>
>
>
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