This issue appears to be caused by a set of bad updates recieved by the Bit Defender application on 9/24/2012. To resolve this problem, please try the steps below:
A) Navigate to the IMail top directory.
B) Locate the folder called "Plugins" and delete it.
C) Double click on "AVUpdate.exe" to force an update to occur. (This process may take several minutes.)
D) If you disabled Bitdefender AV to temporarily allow mail to flow, re-enable BitDefender Antivirus and apply the change.
E) Once the AVUpdate.exe has completed, restart the IMail SMTP and Queue Manager services.
Note: A number of customers have reported that this problem re-occurs with subsequent automatic updates. If you experience this problem repeatedly, please consider temporarily disabling automatic updates as described below:
A) Within the Admin Console, navigate to the Bit Defender AV settings.
B) Uncheck the "Enable Automatic Updates" in the "Updates and Licensing" section and then click "Apply".
C) You may still manually apply updates as described in steps C, D, and E above. However, after the updates have been applied you will need to test mail delivery to ensure the update process succeeded.
If none of these steps resolve the issue please contact our support department for further assistance.
Keywords: Bit Defender, Bitdefender, AV, BD