I noticed recently that our out of office replies are getting blocked by SPAM filters on a regular basis. I come to find that it seems to be caused by the "reply - to" fieled in the header is sent blank. It appears to be an issue that is specific to Exchange 2007. Posini support called this the "Null Sender Dispostion" line within the header. Is there anyway to modify Exchange to populate this field so that the out of office replies will not get blocked? Postini will block these even if the sending domain is white listed. Here is a link to a related article I found, but I haven't been able to find much else. Thank you. http://social.technet.microsoft.com/Forums/en-US/exchangesvrgeneral/thread/2bf53ac6-bba2-4f53-916d-eaaeefd4e5d8

Hi,Yes,with Exchange 2007,Message Disposition Notification (MDN) messages should be sent with blank sender. It is by design.Regards,Xiu