[ale] Sendmail latency

[Ryan Fish]

Mail server info:
RHEL 3 ES
2.4.21-27.0.1.ELsmp
sendmail-8.12.11-4.RHEL3.1

App server info:
RHEL 3 ES
2.4.21-27.0.1.ELsmp

The app server dumps messages from a Java API to the mail server using a transport class.  Sendmail is supposed to then pick up the msgs and send them on their way.  However, for the past 10 days sendmail has been VERY latent in sending these msgs.  10 days ago I rebooted this app server and three others just like it early in the morning after installing several updates via up2date.  A few hours later when I made it to the office I found that no mail was being delivered by the mail server at all.  I would receive transient parse errors ("Transient parse error -- message queued for future delivery") when attempting to send via the cmd line.  I got it going again by starting named on the three internal servers listed in /etc/resolv.conf on the mail server.  It was still slow to deliver messages but I attributed this to the backup in the queue since nothing had been sent anywhere for over four hours.  Anyway, mail is still very latent when the Java app dumps its messages to the mail server so, in my mind, it appears there is some form of a DNS resolution issue on the part of the mail server which is causing the hold up.  As I am still very new at everything and have been thrown into my position (I learn best under fire but must ask tons of questions...) I am in serious need of help with this.  I wish I could offer more info but I really don't know where to start.

based on the output of 'netstat -an | grep :110', 'netstat -an | grep :25' and 'netstat -part | grep sendmail' it does not appear the mail server is being hit by a DOS attack or anything of that nature.

/var/log/maillog doesn't appear to have anything out of the ordinary.  When I tail it in real time I see msgs flowing through the box constantly.

I can successfully send mail from the cmd line with only a slight delay.

I can successfully send mail through POP3 with a slightly longer delay.

I can successfully send mail through the mail server while connected to it from another box in the same network via Telnet on port 25.

I can successfully resolve the app server and the mail server from each other via ping.


As stated before, I am not sure where to start with this so any help will be greatly appreciated.

Thanks in advance.

-Ryan
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