Sendmail rset command hangs socket on 1.6-Release

[Sven Willenberger]

We have a cluster of mail servers, one of which we have upgraded to
1.6-Release (from 1.2) and then subsequently did a fresh install of 1.6
on after the issue first arose.

In essence, using the supplied sendmail and having the connected
sendmail session issue a rset command results in that sendmail process
hanging (only by issuing the telnet ^] command to get to a telnet prompt
and issuing quit can the session be killed). If instead of an rset
command the quit command is issued, the session will end (i.e. the
telnet session terminates) but the sendmail process with "quit" appears
in the process list and will not go away unless killed.

Has anyone seen this odd behavior? At first I thought it was due to a
milter, so I removed it from the .mc file and rebuilt sendmail.cf but no
change in socket behavior. How can I help in terms of troubleshooting?

Sven