This should help more...
2009-02-10 14:34:21,360 FATAL [btpool0-43] [name=username@domain.com;mid=5;ip=192.168.5.32;ua= ZimbraWebClient - FF3.0 (Win)/5.0.0_RC1_1538.UBUNTU6;] system - handler exception
java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:2786)
at java.io.ByteArrayOutputStream.write(ByteArrayOutpu tStream.java:94)
at java.io.OutputStream.write(OutputStream.java:58)
at com.sun.mail.util.BASE64EncoderStream.encode(BASE6 4EncoderStream.java:182)
at com.sun.mail.util.BASE64EncoderStream.write(BASE64 EncoderStream.java:135)
at com.sun.mail.util.BASE64EncoderStream.write(BASE64 EncoderStream.java:96)
at javax.activation.DataHandler.writeTo(DataHandler.j ava:293)
at javax.mail.internet.MimeBodyPart.writeTo(MimeBodyP art.java:1350)
at javax.mail.internet.MimeBodyPart.writeTo(MimeBodyP art.java:845)
at javax.mail.internet.MimeMultipart.writeTo(MimeMult ipart.java:361)
at com.sun.mail.handlers.multipart_mixed.writeTo(mult ipart_mixed.java:85)
at javax.activation.ObjectDataContentHandler.writeTo( DataHandler.java:868)
at javax.activation.DataHandler.writeTo(DataHandler.j ava:301)
at javax.mail.internet.MimeBodyPart.writeTo(MimeBodyP art.java:1350)
at javax.mail.internet.MimeMessage.writeTo(MimeMessag e.java:1683)
at javax.mail.internet.MimeMessage.writeTo(MimeMessag e.java:1659)
at com.zimbra.cs.mime.ParsedMessage.mimeToRaw(ParsedM essage.java:296)
at com.zimbra.cs.mime.ParsedMessage.getRawDigest(Pars edMessage.java:314)
at com.zimbra.cs.mime.ParsedMessage.analyzePart(Parse dMessage.java:652)
at com.zimbra.cs.mime.ParsedMessage.analyzeMessage(Pa rsedMessage.java:588)
at com.zimbra.cs.mime.ParsedMessage.analyze(ParsedMes sage.java:262)
at com.zimbra.cs.mailbox.Mailbox.saveDraft(Mailbox.ja va:3964)
at com.zimbra.cs.service.mail.SaveDraft.handle(SaveDr aft.java:111)
at com.zimbra.soap.SoapEngine.dispatchRequest(SoapEng ine.java:322)
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:189)
at com.zimbra.soap.SoapEngine.dispatch(SoapEngine.jav a:102)
at com.zimbra.soap.SoapServlet.doPost(SoapServlet.jav a:225)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:727)
at com.zimbra.cs.servlet.ZimbraServlet.service(Zimbra Servlet.java:168)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:487)
at org.mortbay.jetty.servlet.ServletHandler$CachedCha in.doFilter(ServletHandler.java:1093)
2009-02-10 14:34:27,525 INFO [main] [] soap - Servlet SoapServlet starting up
2009-02-10 14:34:27,584 INFO [main] [] soap - Adding service AccountService to SoapServlet
2009-02-10 14:34:27,918 INFO [main] [] soap - Adding service MailService to SoapServlet
2009-02-10 14:34:28,131 INFO [main] [] soap - Adding service IMService to SoapServlet
2009-02-10 14:34:28,157 INFO [main] [] misc - version=5.0.0_RC1_1538.UBUNTU6 release=20071002173103 builddate=20071002-1733 buildhost=build13.re.zimbra.com
2009-02-10 14:34:28,158 INFO [main] [] misc - LANG environment is set to: C
2009-02-10 14:34:28,246 INFO [main] [] system - Setting mysql connector property: maxActive=10
2009-02-10 14:34:28,246 INFO [main] [] system - Setting mysql connector property: maxActive=10
2009-02-10 14:34:29,229 INFO [main] [] test - debug_update_config_use_old_scheme = false
2009-02-10 14:34:29,259 INFO [main] [] extensions - Loading extensions from /opt/zimbra/lib/ext
2009-02-10 14:34:29,291 INFO [main] [] extensions - extension com.zimbra.cert.ZimbraCertMgrExt found in /opt/zimbra/lib/ext/zimbra_cert_manager/zimbra_cert_manager.jar
2009-02-10 14:34:29,297 INFO [main] [] extensions - extension com.zimbra.ldaputils.ZimbraLDAPUtil***tension found in /opt/zimbra/lib/ext/zimbraldaputils/zimbraldaputils.jar
2009-02-10 14:34:29,298 INFO [main] [] extensions - extension com.zimbra.cs.nginx.NginxLookupExtension found in /opt/zimbra/lib/ext/nginx-lookup/nginx-lookup.jar
2009-02-10 14:34:29,299 INFO [main] [] extensions - extension com.zimbra.clam.ClamScanner found in /opt/zimbra/lib/ext/clamscanner/clamscanner.jar
2009-02-10 14:34:29,299 INFO [main] [] extensions - Initializing extensions
2009-02-10 14:34:29,411 INFO [main] [] extensions - Initialized extension zimbra_cert_manager:
com.zimbra.cert.ZimbraCertMgrExt@com...t ension.ZimbraExtensionClassLoader@1ad6b4b
2009-02-10 14:34:29,427 INFO [main] [] extensions - Initialized extension zimbrasamba: com.zimbra.ldaputils.ZimbraLDAPUtil***tension@com. zimbra.cs.extension.ZimbraExtensionClassLoader@283 05d
2009-02-10 14:34:29,434 INFO [main] [] extensions - registered handler at /nginx-lookup
2009-02-10 14:34:29,434 INFO [main] [] extensions - Initialized extension nginx-lookup:
com.zimbra.cs.nginx.NginxLookupExten...extension.ZimbraExtensionClassLoader@46d228
2009-02-10 14:34:29,440 INFO [main] [] ClamScanner - attachment scan is disabled