x.2.xxx Mailbox Status

Mailbox status indicates that something having to do with the mailbox has caused this DSN. Mailbox issues are assumed to be under the general control of the recipient.

x.2.0
Other or undefined mailbox status
x.2.1
Mailbox disabled, not accepting messages
x.2.2
Mailbox full
x.2.3
Message length exceeds administrative limit
x.2.4
Mailing list expansion problem