if Cyrus IMAP dies with “User defined signal 1” on Leopard Server and you can’t get the mail server up, look at this post.
http://artins.org/ben/cyrus-imap-dies-with-user-defined-signal-1-on-leopard-server
To Quote: “What’s going on here? To query the status of your cyrus master, servermgrd sends it the USR1 signal. Unfortunately, cyrus master doesn’t install a handler for that signal until after it’s done starting up. Therefore, if the master takes a while to start up, servermgrd is very likely to send the signal before the master is ready to handle it, causing the master to fail to start up. If this happens enough times, launchd will eventually give up on trying to start your mail server.”
For reference, i have included the PDF here.