Hello,
I have CentOS 6 system running 2.6.6 version of postfix. This is low volume mail server with roughly 400
messages being sent through it during the day to my google apps domain. I've ran it for awhile without any issues,
but recently I've started seeing issues with sending emails to my google apps. I've configured spf records to allow
mail from that server, as well as specifically added server's IP to white list and skip spam check lists, which worked
flawlessly for more than two years. Recently, they started refusing to accept my messages with following message.
They would ban access by IP only, as emails from other sources would continue to be delivered.
status=deferred (host ALT1.ASPMX.L.GOOGLE.com[64.233.186.26] said:
450-4.2.1 The user you are trying to contact is receiving mail at a rate that
450-4.2.1 prevents additional messages from being delivered. Please resend your
450-4.2.1 message at a later time. If the user is able to receive mail at that
450-4.2.1 time, your message will be delivered. For more information, please
450-4.2.1 visit 450 4.2.1 https://support.google.com/mail/answer/6592 emailidhere.87 - gsmtp (in reply to RCPT TO command))
I have following configuration lines in main.cf in order not to go over receiving limits of google.
transport_maps = hash:/etc/postfix/transport
default_destination_rate_delay = 12
default_destination_concurrency_limit = 1
default_destination_recipient_limit = 5
slow_initial_destination_concurrency = 1
slow_destination_concurrency_limit = 1
slow_destination_recipient_limit = 5
slow_destination_rate_delay = 12s
and content of transport file:
gmail.com slow:
xxxxx.com slow:
xxxxx.im slow:
xxxxxx.com slow:
According to google, they temporary ban anyone who attempts to connect to their servers more frequently than once a second,
aside from their time sync issues, making five seconds on my end look like less than a second on their, I've noticed that all fresh
emails received by the server will be throttled to be sent every 12 seconds, as I expect; but all deferred emails would attempt
delivery on it's own schedule, without paying attention to the slow delivery rule.
I am wondering if someone could help me to identify what I've missed and how to re-configure my mail server to either:
- make sure that deferred queue is not attempting to deliver messages more frequently than I specified in slow configuration; or
- deliver more than one email to google per connection;
Thank you in advance for your help.
-sashk
