SMTP550DISCONNECT

From Qmail-LDAP Wiki

Disconnect the SMTP session if an 5xx or 4xx error occurs during SMTP conversation.

Default:

off

Affects:

qmail-smtpd

Example:

"" (any value will do)

Note:

• This is useful to
  • prevent a spammer from hanging SMTP session by using it along with 550GREETING or 421GREETING, or
  • prevent a spammer trying different senders or recipients in the same session separated by rset's
  • It can produce an increment of opened SMTP sockets, since the SO will keep the SMTP sockets in TIME_WAIT status during the timeout configured for this state (usually: 60 seconds).