Hier soll beschrieben werden, wie man am besten Postfix als Backup-MX einsetzt - er soll also Mail für gewisse Domains annehmen und solange zwischenspeichern, bis der Primary MX wieder online ist - und dann auch die gespeicherten Mails automatisch dort hin zustellen.

Ideensammlung (unfertig)

1

maximal_backoff_time = 4000
maximal_queue_lifetime = 5
minimal_backoff_time = 1000
queue_run_delay = 1000

2

If you use the permit_mx_backup feature, then you should be all set. The only problem with it is that people can list you as backup relay without your permission.

The permit_mx_backup restriction looks at the DNS, not at the relay_domains parameter. If a host lists you as their backup, then permit_mx_backup will accept the mail.

Re: faster flushing: you can tweak the {min,max}imal_backoff_time parameters.

• If you're significantly decreasing them, of course you also need

to modify queue_run_delay to be smaller than minimal_backoff_time, and it should probably be half minimal_backoff_time or even smaller.

3

smtpd_recipient_restrictions = permit_mx_backup,

• permit_mynetworks, check_relay_domains

The server is functioning properly when the primary mx is donw. Question is could someone else use my server in their DNS as their mx backup.

permit_mx_backup will relay mail if your MTA is listed as backup, either by host name or by IP address(1).

• Wietse

(1) This requires that the IP address of the MTA, as configured on

• its own network interface, is the address listed in the DNS.