Here is my information:
$ zmcontrol -v
Release 7.2.1_GA_2790.RHEL6_64_20120815212147 UNKNOWN_64 FOSS edition.

I noticed that the zimbra java process has been using ~150% of CPU lately causing mail to crawl to a halt and then return back to normal. It does this many times an hour.

I checked /opt/zimbra/log/mailbox.log and found these messages:

Code:
2013-05-21 12:17:47,075 INFO  [main] [] tnef - Calendaring TNEF message mapped to ICALENDAR with UID=040000008200E00074C5B7101A82E00800000000801B1390ADDFCD010000000000000000100000004C0ECBA396F6C8449E7644CFFA475043
2013-05-21 12:17:47,600 INFO  [main] [] tnef - Calendaring TNEF message mapped to ICALENDAR with UID=040000008200E00074C5B7101A82E00800000000801B1390ADDFCD010000000000000000100000004C0ECBA396F6C8449E7644CFFA475043
2013-05-21 12:17:48,134 INFO  [main] [] tnef - Calendaring TNEF message mapped to ICALENDAR with UID=040000008200E00074C5B7101A82E00800000000801B1390ADDFCD010000000000000000100000004C0ECBA396F6C8449E7644CFFA475043
2013-05-21 12:17:48,629 INFO  [main] [] tnef - Calendaring TNEF message mapped to ICALENDAR with UID=040000008200E00074C5B7101A82E00800000000801B1390ADDFCD010000000000000000100000004C0ECBA396F6C8449E7644CFFA475043
2013-05-21 12:17:49,173 INFO  [main] [] tnef - Calendaring TNEF message mapped to ICALENDAR with UID=040000008200E00074C5B7101A82E00800000000801B1390ADDFCD010000000000000000100000004C0ECBA396F6C8449E7644CFFA475043
It continues until it runs out of memory:

Code:
2013-05-21 12:17:52,913 FATAL [main] [] system - out of memory
java.lang.OutOfMemoryError: Java heap space
        at java.util.Arrays.copyOf(Arrays.java:2882)
        at java.lang.AbstractStringBuilder.expandCapacity(AbstractStringBuilder.java:100)
        at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:390)
        at java.lang.StringBuilder.append(StringBuilder.java:119)
        at com.zimbra.cs.mime.ParsedMessage.getMainBodyLuceneDocument(ParsedMessage.java:924)
        at com.zimbra.cs.mime.ParsedMessage.analyzeNonBodyParts(ParsedMessage.java:428)
        at com.zimbra.cs.mime.ParsedMessage.analyzeFully(ParsedMessage.java:454)
        at com.zimbra.cs.mailbox.CalendarItem.getIndexDocuments(CalendarItem.java:380)
        at com.zimbra.cs.mailbox.CalendarItem.generateIndexData(CalendarItem.java:258)
        at com.zimbra.cs.mailbox.IndexHelper.indexItemList(IndexHelper.java:849)
        at com.zimbra.cs.mailbox.IndexHelper.indexDeferredItemsInternal(IndexHelper.java:375)
        at com.zimbra.cs.mailbox.IndexHelper.indexDeferredItems(IndexHelper.java:295)
        at com.zimbra.cs.mailbox.IndexHelper.maybeIndexDeferredItems(IndexHelper.java:251)
        at com.zimbra.cs.mailbox.Mailbox.addMessage(Mailbox.java:4745)
        at com.zimbra.cs.mailbox.Mailbox.addMessage(Mailbox.java:4738)
        at com.zimbra.cs.mailbox.Mailbox.addMessage(Mailbox.java:4726)
        at com.zimbra.cs.redolog.op.CreateMessage.redo(CreateMessage.java:427)
        at com.zimbra.cs.redolog.RedoPlayer.runCrashRecovery(RedoPlayer.java:443)
        at com.zimbra.cs.redolog.RedoLogManager.start(RedoLogManager.java:229)
        at com.zimbra.cs.redolog.DefaultRedoLogProvider.startup(DefaultRedoLogProvider.java:41)
        at com.zimbra.cs.util.Zimbra.startup(Zimbra.java:226)
        at com.zimbra.cs.util.Zimbra.startup(Zimbra.java:127)
        at com.zimbra.soap.SoapServlet.init(SoapServlet.java:130)
        at javax.servlet.GenericServlet.init(GenericServlet.java:241)
        at org.mortbay.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:440)
        at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:263)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
        at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
        at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
        at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1254)
        at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
        at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:471)
2013-05-21 12:17:54,816 INFO  [main] [] soap - Servlet SoapServlet starting up
2013-05-21 12:17:54,840 INFO  [main] [] soap - Adding service AccountService to SoapServlet
2013-05-21 12:17:54,894 INFO  [main] [] soap - Adding service MailService to SoapServlet
2013-05-21 12:17:54,991 INFO  [main] [] soap - Adding service IMService to SoapServlet
2013-05-21 12:17:54,999 INFO  [main] [] misc - version=7.2.1_GA_2790 release=20120815212147 builddate=20120815-2126 buildhost=zre-rhel6-64.eng.vmware.com
2013-05-21 12:17:55,000 INFO  [main] [] misc - LANG environment is set to: C
2013-05-21 12:17:55,000 INFO  [main] [] misc - System property java.home=/opt/zimbra/jdk1.6.0_33/jre
2013-05-21 12:17:55,000 INFO  [main] [] misc - System property java.runtime.version=1.6.0_33-b03
It finally restarts, and everything returns back to normal but then a few minutes later, the "Calendaring TNEF message mapped..." messages start all over again.

I checked zimbra file permissions, and it says that it fixed them. I have found No-Such-Blob errors but I don't know if they are related.

All other configuration appears to be normal.

I would appreciate any suggestions.

Thank you!