This feature essentially bounces all unknown message
trying to connect to your server. However, emails from Trusted Senders
and White listed IP’s will automatically bypass Greylisting and are
delivered directly to the Spool.
The premise is that Spammers create scripts that bombard your server
with emails. These messages are then bounced back to their sending
email server. Since, most Spammers email is not coming from a valid
email server, the messages are not retried and therefore this reduces
the amount of SPAM that your customers receive.
For those messages that are returned to valid email servers, the
messages will be retried at least four times. If the first retry is
beyond the Block period (default 15 minutes) and within the Pass Period
(default 6 hours) the message is passed to the Spool and it goes through
its normal processing. A record is also created that says this is a
valid email address and keeps it for 36 days (default). If another
email from the same email address is received within the 36 day, record
clock is reset for an additional 36 days and delivered directly to the
Spool.
ReferenceArticle ID: 93, Created On: 8/29/2011, Modified: 8/29/2011