Hi,
Please double check if this subscriber has an inbox that is close to the full limit or if he already has exceeded this limit. If the users email box is full then unity can not send the message from that user so this is causing the problem.
I think since the subscriber is prohibited from sending at the moment due to mailbox size, Unity is sending the message on their behalf, they are definitely past the prohibit send limit. Please check the affected user's mailbox limit size.
When the mailbox drops within limits again, voicemail message subject header in email
should appear normally.
There's a defect on this:
http://wwwin-metrics.cisco.com/cgi-bin/ddtsdisp.cgi?id=CSCsb76438
It was fixed in 4.2(1).
Check the following Registry key:
HKLM\Software\Active Voice\Conversations\1.0\DisableISMSystemWide
Make sure it is set to 0.
HTH
//G