Glo Networks Technical Blog (Glo Blog)

Default behaviour of distribution groups, in Exchange 2007

By default, in Exchange 2007, distribution groups cannot be mailed without authentication. This means that any distribution group that receives external mail will respond with a rejection, until this default behaviour is altered.

#5.7.1 smtp;550 5.7.1 RESOLVER.RST.AuthRequired; authentication required

A good idea in the face of spam, except that this change in behaviour isn’t really shouted about much in the documentation.

The GUI way to alter this is to head into the Exchange 2007 Console, head into the properities of the distribution group, and then the Mail Flow Settings. Select Message Delivery Restrictions and then click Properties. Untick “Require that all senders are authenticated”.