Client originally had a 27gig mail.que file. Ran a eseutil and the mail.que went downto 2.064kb. Now it's back to 3 gigs again.What would be causing this?Is there any logging that could be done to investigate what is going on?

What version of Exchange?

Troubleshooting: 1. Please describe the exchange topology 2. Is there any error event in the application log on the exchange servers when the mail queue was growing? 3. Please verify if theres any corruption in the databases (Reference) 4. Please go to mailbox server, launch Perfmon to monitor the following counter, see if there has stuck a lot of messages: "MSExchangeIS Mailbox/Messages Queued for Submission"->StorageGroupName\DatabaseName 5. The database size increase can be caused if users are sending larger messages, we can use message tracking log to check the sizes of messages during that period of time 6. Please set the receive connector to verbose mode, and monitor the SMTP log files when the mail queue is growing dramatically 7. Please run ExBPA against exchange servers for a health check 8. Please recycle the transport service, and check the issue 9. It can also be caused by old client, please ensure that all clients have patched to outlook 2003 SP3 or later version (KB 908507). In older legacy clients (i.e. OL2003 SP1), if an oversized message streaming to the database that is subsequently rejected due to exceeding max size limits, it remains in the client and is resubmitted again after the message is rejected by store due to size limits Resources: Working with the Queue Database on Transport Servers Understanding Back Pressure

Single Exchange 2007 on a SBS 2008 with journaling enabled. I'll get the rest of the information for you.

Cool

How does the mail.que file grow so large? Whenever ours goes over 1 GB, the transport service shuts down. Exchange 2007 SP1 + HF7.