I've been having problems with my home Zimbra server dropping connections to clients (both Apple Mail and Mutt, where it's really noticeable). I've used the same mutt client to connect to both my work (NE on RH) and home (FOSS on Ubuntu), and the client always has disconnect problems talking to my home server.

It's really annoying in that the connection is almost always dropped when I'm responding to a message in vi. When I go to send the message, mutt no longer has a connection and can't save the message into Sent via IMAP.

I'm not 100% sure, but this may be a new problem in 5.x. I don't recall it doing it in 4.5, but I could be wrong.

mailbox.log shows this logged every time a connection is dropped:

2008-02-17 16:08:16,314 INFO [ImapSSLServer-306] [] ProtocolHandler - Exception occurred while handling connection
java.net.SocketException: Socket closed
at java.net.SocketInputStream.read(SocketInputStream. java:162)
at com.sun.net.ssl.internal.ssl.InputRecord.readFully (InputRecord.java:293)
at com.sun.net.ssl.internal.ssl.InputRecord.read(Inpu tRecord.java:331)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRec ord(SSLSocketImpl.java:789)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readDat aRecord(SSLSocketImpl.java:746)
at com.sun.net.ssl.internal.ssl.AppInputStream.read(A ppInputStream.java:75)
at java.io.BufferedInputStream.fill(BufferedInputStre am.java:218)
at java.io.BufferedInputStream.read(BufferedInputStre am.java:237)
at com.zimbra.cs.tcpserver.TcpServerInputStream.readL ine(TcpServerInputStream.java:73)
at com.zimbra.cs.imap.TcpImapRequest.continuation(Tcp ImapRequest.java:54)
at com.zimbra.cs.imap.TcpImapHandler.processCommand(T cpImapHandler.java:109)
at com.zimbra.cs.tcpserver.ProtocolHandler.processCon nection(ProtocolHandler.java:160)
at com.zimbra.cs.tcpserver.ProtocolHandler.run(Protoc olHandler.java:128)
at EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Wo rker.run(Unknown Source)
at java.lang.Thread.run(Thread.java:619)