Question : Sendmail Error 451 4.7.1 and Illegal Seek

We have been having a problem lately with our two sendmail machines.  We have had them for a long time, and they have always been reliable until recently.  Currently these two sendmail machines are our outside relays. They accept mail, then relay to our spam box, which then relays to our Exchange server.  This was all working correctly until recently.

Now, several times a day, the two sendmail queues stop.  It appears that an email comes into the queue and causes a "451 4.7.1 Please try again later" error.  Once that error occurs then all the other emails that appear to come in behind it receive the illegal seek error.  The queues then appear to stop.  

Generally rebooting will not fix the problem.   And it seems that issuing a sendmail -q doesnt always fix it.   It seems to me that the machines have to queue up over 100 messages, before sendmail -q will do anything.  If I issue before that, it instantly comes back to the prompt.  When it does work, the queue clears out, except for the original message that caused the 451 4.7.1.

I am very new to sendmail, and only can relate what I know through trying to diagnose this problem.

Both boxes are running Suse 7.2 with sendmail 8.11.2.

The spambox is a third party appliance running solaris and sendmail 8.12 (I believe)

The email that causes the jam is always a piece of spam, and for some reason is always ~650 bytes.

Any help would be appreciated!!!

Answer : Sendmail Error 451 4.7.1 and Illegal Seek

The absence of anything captured by tcpdump on the first 'sendmail -v -q'  and the presence of network traffic on the second run pretty clearly indicates that the problem is the Sendmail relay servers.

I know that this sort of a problem isn't a generic flaw in Sendmail, so that leaves the local implementation as suspect. Possible causes include a lack of free space on /var/spool, a flaw in the implementation of one of the system libraries Sendmail uses, a flaw in the build of Sendmail. or some kernel problem.

Checking disk free space should be pretty easy with 'df -k /var/spool'.

Is your SuSE 7.2 up to date with respect to the SuSE updates?