Firstly thanks for any help provided, this is my first post here so I'll be happy to receive any feedback!
Now, we have had a Zimbra 5.0.6 installation for about 20 months now, and it has around 800 accounts in it now. In the last week or so we have been getting complaints from clients about the connection timing out when sending out messages. When the mail client tried to copy the message to the Sent folder the connection would time out. But since the problem appears to have spread to most of the accounts, and I have been able to replicate the error myself. The connection seems to timeout quite randomly, but it's happening a lot (around 50% of the time).
Looking at mailboxd.log, there's occasionally the following exception coming up (not sure if it's related):
2010-01-18 10:53:55,012 INFO [ImapServer-16212]  ProtocolHandler - Exception occurred while handling connection
java.net.SocketException: Socket closed
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream. java:129)
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:782)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readDat aRecord(SSLSocketImpl.java:739)
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:235)
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:107)
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)
The Datacenter hosting the machine as well as the client's ISP have reported they are not having any sort of network problems. Could this simply be due to too high usage on the server? The CPU usage has been around 50% on average during working hours. Are there any memory or CPU settings I can change to optimize Zimbra? It's the only service running on that server, so we can crank it up to full!
Please let me know if I can provide any more info!
Thanks a lot!
Andre, the desperate sysadmin!