Read and understand the
active queue and
deferred queue discussions in the
In case of slow delivery, run the qshape tool as described
Submit multiple recipients per message instead of submitting
messages with only a few recipients.
Submit mail via SMTP instead of /usr/sbin/sendmail. You
may have to adjust the
smtpd_recipient_limit parameter setting.
Don't overwhelm the disk with mail submissions. Optimize
the mail submission rate by tuning the number of parallel submissions
and/or by tuning the Postfix
in_flow_delay parameter setting.
Run a local name server to reduce slow-down due to DNS
lookups. If you run multiple Postfix systems, point each local name
server to a shared forwarding server to reduce the number of lookups
across the upstream network link.
values so that Postfix does not waste lots of time connecting
to non-responding remote SMTP servers.
Use a dedicated mail delivery transport for problematic
destinations, with reduced timeouts and with adjusted concurrency.
Tuning the number of simultaneous deliveries"
fallback_relay host for mail that cannot be delivered
upon the first attempt. This "graveyard" machine can use shorter
retry times for difficult to reach destinations. See "Tuning the frequency of deferred mail delivery
Speed up disk updates with a large (64MB) persistent write
cache. This allows disk updates to be sorted for optimal access
speed without compromising file system integrity when the system
Use a solid-state disk (a persistent RAM disk). This
is an expensive solution that should be used in combination
with short SMTP timeouts and a
machine that delivers mail for problem destinations.