After upgrading to FreePBX 2.9.0.7, I noticed that if you have follow me setup on an extension, e-mail notifications for new voice mail will not be sent unless that extension has at least one voice mail message (new or old) in it. To be crystal clear, if you have at least one (new or old) voice mail message in that users extension, e-mail WILL be sent on all subsequent new voice messages. Removing the follow me for that extension rectifies the problem. This wasn't an issue in 2.8. I've tested this quite thoroughly.