today I got the following mail from Postmaster at getronics.com (Getronics
being an ICT company with many thousands of employees, spread over several
The sending system (IP address <my MTA's IP address here>) apparently retries delivery
only every two hours. The intial retry after a 421 status should be less
than 30 minutes. Please refer to RFC 2821, section 184.108.40.206 "Sending
Strategy", where the recommended first retry should be 30 minutes, and there
should be two retries within the first hour. The initial retry after a 421
status should probably be somewhat shorter (say 15 - 20 minutes).
The problem here is that the greylisting mechanism used by Getronics
remembers the connection attempt for only one hour. After that the next
connection is seen as if was a new, and not a retried, connection and it's
The owner of the sending server should adjust the first two retry intervals
(and certainly the first one) to fall within the recommendation made in
RFC2821 to avoid problems when interacting with other email systems.
Am I misinterpreting RFC2821 in that (IMO) there is no such requirement as
It is not my intention to start a (flame) war on greylisting, but keeping
greylist information for only one hour needs a reality check, isn't it? I know
at least two mature and well-known MTA implementations that have a default
retry interval which doens't match the requirements of this domain.