x.3.xxx Mail System Status

Mail system status indicates that something having to do with the destination system has caused this DSN. System issues are assumed to be under the general control of the destination system administrator.

x.3.0
Other or undefined mail system status
x.3.1
Mail system full
x.3.2
System not accepting network messages
x.3.3
System not capable of selected features
x.3.4
Message too big for system
x.3.5
System incorrectly configured