Assume that you create a retention policy for voice mail messages in Microsoft Exchange Server 2010. When you receive a voice mail message that is Information Rights Management (IRM) protected, the retention policy is not applied to the voice mail message.
Note If you remove IRM protection, the retention policy is applied to the voice mail messages.
This issue occurs because a default policy tag (DPT) set with a message class of voice mail only works for messages that have the IPM.Note.Microsoft.Voicemail* message class. However, IRM protected messages have the IPM.Note.rpmsg.Microsoft.Voicemail* message class. Therefore, the retention policy is not applied to the voice mail message that is IRM protected.