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sendmail connection timed out

Luc Monnens
Frequent Advisor

sendmail connection timed out

Hi all,

We have been using sendmail on a hp-ux 11.00 (yes I know) server to script automated email messages to trigger a user action for a couple of years now.
Recently something must have changed on our server/network so these emails do not get delivered anymore.

When I send a manual test mail from the commandline:
"/usr/sbin/sendmail -v" (and then write the test message ended with a single dot alone on the last line) I get
" Connecting to via esmtp..."
and a bit later
" Deferred: Connection timed out with" is an entry in the /etc/hosts file on the server I use sendmail on

When I do "telnet 25" where is the IP address of my email server (and the IP address for in my /etc/hosts file) I get
"Trying ..."
and then a bit later
"telnet: Unable to connect to remote host: Connection timed out"

I can ping ok and traceroute gets to the IP and fine

So why is sendmail timing out?

Where should I look? What logs could tell me something more?
Is it routing?
Is it DNS?
Is it something else?

Are there other tools beside ping, traceroute and telnetting to port 25 to pinpoint this?

If this is not the correct forum for this and you would recommend I take this to the networking one, please let me know and I close it here and take it there.

Looking forward to your input

Thank you.

Luc Monnens



P.S. This thread has been moved from HP-UX > System Administration to HP-UX > messaging - HP Forums Moderator

Keith Johnson
Valued Contributor

Re: sendmail connection timed out

First, I'd look in the mail log - /var/adm/syslog/mail.log for any sort of error messages. Also, make make sure the Sendmail daemon is running. Also, if you aren't using DNS resolution on the server from which you're sending mail, make sure your /etc/nsswitch.conf file is configured correctly.
No matter where you go...there you are.
Luc Monnens
Frequent Advisor

Re: sendmail connection timed out

Hi Keith,

the mail.log only shows me these "Connection timed out with"

ps -ef | grep sendmail gives me:
"sendmail: accepting connections on port 25"
so I guess that is fine.

nsswitch.conf is having "files" first for all - and as said there is an entry for in my "/etc/hosts".

Two more pieces of information.
1. is an internal server of ours (on another network)

when I do a sendmail "" for instance, I get all the expected sendmail info back from the server.

That is also why I think it is not a sendmail issue - which config we did not touch anyway - but a networking one.

Kind regards,

Steven Schweda
Honored Contributor

Re: sendmail connection timed out

> Is it routing?


> Is it DNS?

Unlikely. Wrong complaint.

> Is it something else?

Could be a firewall.

> Are there other tools beside [...]

Probably, but I like those. If "telnet 25" also fails, that would
explain why sendmail fails. If plain "telnet" (or by name) works, then it's
not a simple routing problem. "ping" working
should be similar.
Luc Monnens
Frequent Advisor

Re: sendmail connection timed out

It turned out to be a routing issue.