XCON: Message Transfer Agent Replaces DDA Type "RFC-822" with DDA Type "SMTP" After Installing Service Pack 3

Under certain conditions, the Exchange Server 5.5. Service Pack 3 (SP3) message transfer agent (MTA) replaces the X.400 Header Field value of the domain-defined attribute (DDA) Type RFC-822 with the value "SMTP". This replacement can cause messages to not be delivered.

Exchange Server 5.5 SP3 introduces additional functionality to the MTA, including modifications to X.400 header handling. When this MTA receives an incoming message that contains an O/R address with a DDA Type of RFC-822, and is required to relay the message, it may change the DDA Type to SMTP before relaying the message. This issue does not occur in earlier versions of Exchange Server 5.5.

To resolve this problem, obtain the latest service pack for Exchange Server 5.5. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

Microsoft has confirmed that this is a problem in Microsoft Exchange Server version 5.5 Service Pack 3. This problem was first corrected in Exchange Server 5.5 Service Pack 4.