Connection being lost to remote SMTP server?

Greetings!

Occasionally, I'm seeing messages sit on the queue for very long periods of
time. Looking through the logs, on each time the queue would run, the log
for such messages would be "Spool file is locked". I next found with "ps" that
the (I assume) original process for each such message still existed, clearly
showing why the file was still locked :)

I find that whenever I use exiwhat, the messages are then delivered. So far,
each time I've seen this, it has been to the same remote machine, which is
an SMTP to Banyan VINES gateway. I suspect the problem is, at least in part,
with the remote machine, but what I'm posting to this list for is to see if anyone
has any Exim and/or Unix ideas on tracking down exactly what is occuring. Or has
an idea on what could be causing this problem. Or maybe a better idea of a
workaround than the kludge I've done of running exiwhat once an hour via cron :)

-------------------------
John C. Ring, Jr.
jcring@???
Network Specialist
Union Switch & Signal Inc.