XADM: NDR When Attempting to Send to Large Number of Recipients

If you attempt to send a message to 10 or more recipients or send a message that is larger than 4,096 bytes, the message may appear in the Outbox for an unusually long time and then you may receive a non- delivery report (NDR) that contains the following text:

When data is written to the message transfer agent (MTA), a 16-KB buffer is used. If the server attempts to transfer more than 16 KB at a time, you may experience the symptoms described above.

When a message is addressed to fewer than 10 recipients or is 4,096 bytes or smaller, one recipient descriptor is transferred at a time. In this case, the server rarely exceeds the 16-KB buffer limit for writing data to the MTA. However, when a message is addressed to 10 or more recipients or is larger than 4,096 bytes, ten recipient descriptors are transferred at a time instead of one. When this occurs, the server frequently exceeds the 16- KB buffer limit.

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.0. This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 5.0. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):