Sounds like you could be hitting CSCae05933. By default in 3.1(3) you can still run into the situation where messages are "backed up" in the \commserver\UnityMTA directory. If you go look in that directory, I'll be you see a bunch of messages in there. The release notes for the above bug have the work around for this:
=======================
CSV import of subscribers may contain spaces after the last name or first
name. Where the example "Last ,First ,1234" shows spaces after First and
Last names when the following is expected "Last,First,1234"
Messages in the MTA directory may not all have the condition. Only one
message with the condition will cause all others to remain in the UnityMTA
without delivery. See workarounds below.
Workaround:
To correct the CSV files before import, find and replace any string like
" ," (no quotes) with "," (no quotes).
If subscribers have been imported and message delivery is failing:
Per CSCdw41721
If you are running Unity 3.0(4) or Unity 3.1(3), you can add a registry key to
enable
the automatic moving of blocking messages to a specified directory for
undeliverable messages.
To enable this do the following (assumes Unity is installed on C:, modify the
drive letter as needed):
1) Stop AvUmrSyncSvr service
2) Create a directory called Failed in c:\Commserver\unityMTA
3) Run regedit and add the following registry key:
HKLM/Software/ActiveVoice/UnityUMR/1.0/MtaFailedPath =
c:\Commserver\unityMTA\Failed
4) Start AvUmrSyncSvr service
With this key in place, whenever a message is moved to the failed directory,
an information message will appear in the application event viewer. This
information should be used to repair or recreate the accounts of the
recipients
of the failed messages.
If this fix is not available in your version of Cisco Unity, use the
information
below to prevent the problem from happening again after it is discovered on
your Unity system:
1. Go to the MTA directory (located in \Commserver\unityMTA.) Move all of the
messages (including each messages associated text file) in this directory to
another directory, then move each message and associated text file
back to the UnityMTA directory one at a time, stopping and starting the
AvUMRSyncSvr service each time. You will see which messages are
delivered and which are causing the problem. Remove these undeliverable message
(s) from the MTA directory.
2. Determine the affected subscriber(s) from Step 1, and repair or recreate
their account(s) on Cisco Unity. Possible causes include no Exhchange mail
box, or a failed import during a 2.4.6 upgrade.
As the subscribers imported with the condition above have messages appear
in the failed directory, delete and recreate these accounts. If several
accounts exist, creating another CSV file without the spaces after the name
will allow a faster import.
