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mail server. If SX-GATE hosts the catch-all mailbox, you can disable it with the
option "Emails to unknown local recipients" on the same tab. If however you must
continue with a catch-all setup, this greylisting option will help to reduce both, SX-
GATE's workload and the amount of SPAM.
permit mail partners
Basically every inbound email has to pass greylisting in this mode. However SX-
GATE will extract the sender and recipient of each outbound email and whitelist
the reverse address combination for inbound mails. So replies and also any further
message exchange using the same addresses is no longer subject to delays. The
actual sender IP is not considered. Each outgoing email with the same address
combination will refresh the clearance. If it is no longer used, it will expire in
accordance with "Timeout after last use.
While an effort is made to avoid delays for correspondence
initiated by a local user, initial submissions of a remote
user will be deferred. Therefore it is crucial to manually
add important sender and recipient addresses to "Recipient
whitelist" and "Recipient whitelist" respectively. Explain the
prospective delays to the local users, as the delays will
particularly hit in the early stages.
always active
This setting enables "pure" greylisting. Each inbound mail will be delayed, except
the combination of its IP, sender and recipient is already known.
To avoid annoyance we highly recommend to explain
the prospective delays to the local users and fill out
the "Recipient whitelist" and the "Recipient whitelist" in
advance.
Accept delivery after at least
If a combination of source IP, sender and recipient is not known by the greylist, this
parameter controls after how many minutes subsequent connections using the same
combination will be accepted. So a retransmission will not succeed until this minimum
delay has passed off.
If a retransmission occurs beforehand it will be aborted with
a temporary error, too. However this will not prolong the time
remaining until it is unblocked.
