When a Postfix delivery agent decides that mail must be delivered
later, it sends the destination domain name and the queue file name
to the
flush(8) daemon which maintains per-destination logfiles
with file names of queued mail. These logfiles are kept below
$
queue_directory/flush. Per-destination logfiles are maintained
only for destinations that are listed with the $
fast_flush_domains
parameter and that have syntactically valid domain names.
Postfix
delivery
agent |
-(domain, queue ID)-> |
Postfix
flush
daemon |
-(queue ID)-> |
One logfile
per eligible
domain |
When Postfix receives a request to "deliver mail for a domain
now", the
flush(8) daemon moves all
deferred queue files that are
listed for that domain to the
incoming queue, and requests that
the queue manager deliver them. In order to force delivery, the
queue manager temporarily ignores the lists of undeliverable
destinations: the volatile in-memory list of dead domains, and
the list of message delivery transports specified with the
defer_transports configuration parameter.
