Fedora Networking :: Sendmail Doesn't Send Email For Several Days In Spite Of Being Online?

I have the following problem with sendmail on F14 (had the same on F13 already):

I have a network setup using bridging which is controlled through traditional ifup/ifdown (because NetworkManager can't handle bridging). My sendmail configuration differs from the Fedora default only by having a SMART_HOST relay. The queueing interval in /etc/sysconfig/sendmail is the default (1h).

When my network connection is up, sendmail normally sends email through the relay immediately. Sometimes I have to interrupt the connection for a few minutes. When my network connection is down, sendmail starts queueing email (OK this far). When the network connection comes back up, I'd expect sendmail to restart sending mail through the relay again. But sometimes, that doesn't happen. Instead, sendmail keeps queueing my mail infinitely (I have seen it happen for several days) until I finally notice that my email isn't received, and run sendmail -q by hand (by that time, my boss is already angry that I'm not responding to his email). In that state, even new mail is queued rather than forwarded by sendmail. It appears that the only way to stop that behavior is to restart the sendmail service.