You have a Microsoft Exchange Server 2010 mailbox.
You send an email message to a recipient by using this mailbox.
The subject line of the email message contains unsupported encoded characters, such as ISO-2022-JP-2 encoded characters.
In this scenario, the email message is not delivered to the recipient. Additionally, you do not receive a non-delivery report (NDR) message.
This issue occurs because Exchange Server 2010 does not process an email message if the subject line contains unsupported encoded characters. Additionally, an exception occurs when Exchange Server 2010 tries to generate a NDR message.
To resolve this issue, install the following update rollup:
2579150 Description of Update Rollup 4 for Exchange Server 2010 Service Pack 1
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.