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Sendmail server alias problem

 
Andrew Kaplan
Super Advisor

Sendmail server alias problem

Hi there --

We have a sendmail server in operation and I noticed that an alias of the server does not appear to be working.

The server is known by two names, and when I do an nslookup of both names, the output indicates that both names appear to be configured on the internal network DNS servers. However, when I do the same using an external DNS server, the alias comes back as a non-authoritative record.

The problem that I am seeing is the following: If I send an e-mail to alias of the server from a remote host, the message does not get through. The message does get through if I am on the server itself.

I'm guessing the non-authoritative record on the external DNS server is causing this, but before I go there I wanted to know if there is something else I should check. Thanks.
A Journey In The Quest Of Knowledge
10 REPLIES
Ivan Ferreira
Honored Contributor

Re: Sendmail server alias problem

>>> However, when I do the same using an external DNS server, the alias comes back as a non-authoritative record.

This is normal, a non authoritative record is just a record that was answered from a server that does not owns the zone, it's cached information.

Can you confirm in the /var/log/maillog that the mail reach the server?
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Andrew Kaplan
Super Advisor

Re: Sendmail server alias problem

Hi there --

I checked the maillog file, and there is no record of the message reaching the server.
A Journey In The Quest Of Knowledge
Ivan Ferreira
Honored Contributor

Re: Sendmail server alias problem

From a remote host, do:

telnet alias_of_server.domain 25

Can you connect? Can you send an message using SMTP?

MAIL FROM: username@domain.com
RCPT TO: username@yourdomain.com
DATA:
Subject: Test
Test
.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Andrew Kaplan
Super Advisor

Re: Sendmail server alias problem

Hi there --

I could not open a telnet connection to port 25 using the alias of host.
A Journey In The Quest Of Knowledge
Alexander Chuzhoy
Honored Contributor

Re: Sendmail server alias problem

if you do "ping alias_of_mail_server"
do you get reply from the correct IP?

Andrew Kaplan
Super Advisor

Re: Sendmail server alias problem

Ping won't work due to network security issues. A ping of the alias on the localhost returns the hostname and the correct address.
A Journey In The Quest Of Knowledge
Alexander Chuzhoy
Honored Contributor

Re: Sendmail server alias problem

security issues?

Could it be that the required for communication ports are simply blocked by firewall and that's the reason why you can't access your mail server from remote?
Try to close the firewall and see if the problem dissapears.
Andrew Kaplan
Super Advisor

Re: Sendmail server alias problem

Hi there --

I can access the webserver remotely via the hostname. It is only the alias that I am having problems with at this time.

A Journey In The Quest Of Knowledge
Andrew Kaplan
Super Advisor

Re: Sendmail server alias problem

Excuse me...I meant e-mail server. The server does have a web interface and I can access it using either the hostname or the alias. It is strictly the delivery of mail when using an e-mail address that inludes the alias that there is a problem.
A Journey In The Quest Of Knowledge
Steven E. Protter
Exalted Contributor

Re: Sendmail server alias problem

Shalom,

Possibilities:
1) Your firewall is blocking by name, not ip address. This would lead me to believe the results where your telnet hostname 25 works on one hostname and not the other. Anyway firewall is worth checking. No matter what your alias sitution, if you can't connect on port 25 the mail server is as useful as a brick at least for the one domain.

2) You original message leads me to believe that there is some barrier between the mail and the server otherwise there would be something on the maillog that would indicate as to why the failure is happening.

All evidence points to an exteran issue.

iptables -L

Take a look at syslog with a tail -f as you attempt your mail test.

SEP
Steven E Protter
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