Sendmail 8.8.7 stucks

[Anu Mathew]

My sendmail server handles huge outbound mail queues. Every queue has about 2300-7000 recipients. During the running of each queue, sometimes sendmail takes long time. While checking the process details, it displays "Client DATA status" or "Client Data 354" and this stays for about 10-20 minutes. obviously, the entire queue is delayed many times, due to this problem.

I can easily telnet into the port 25 of these clients, and their response is faster. The two MDAs establish the connection, and are very reluctant or shy to complete the data xfer. Just they stare face to face...No talking.
(The timeouts defined in sendmail.cf seems to be fine.)

If I use our ISP's server as my relay, this does not occur. But the problem is that mails routed thru their server takes longer time to reach the destination.

I could not find much info on this phenomenon till now. If any one can shed some light into this, it will be a great help.

Thanks in advance for your time and patience.

Thanks,

Anu Mathew

[Christopher Caldwell]

Not sure about why your having a slowdown, however, if you sort the recipient list in domain order, you'll find that you can gain substantial performance improvements. sendmail caches connections, so you don't have the overhead of connection setup. Moreover, if there are numerous recipients at a given domain, the message will delivered to blocks of this users per iteration when sendmail delivers the mail.

(None of this will work if you're relaying though someone who's not the relay (MX) for the final destination of the mail).

[Anu Mathew]

Thanks for the response. Our lists are sorted by domain names. Besides, the above said error happens mainly to single recipient mails as well.

Anu Mathew

[Christopher Caldwell]

Have you looked at the settings of identd in sendmail.cf?
#O Timeout.ident=30s

You might try
O Timeout.ident=0s

Also, are you running a caching name server?

[Anu Mathew]

Is not Ident more used with the inbound connections of the sendmail? I dont have any visible problems with the in-bound connections to the server.

I use the ISPs domain servers. I am not running any caching servers.

Thanks,

Anu Mathew

[Frank Li]

When you issue " mailq " on the sendmail server , what's the output ?

[Ralf Hildebrandt]

It might just be that the link is slow. Don't want to troll you, but you can significantly increase performance if you switch to Postfix (www.postfix.org) -- and also you get a asecurity bonus (8.8.7 has known security bugs).