LinuxQuestions.org - Postfix: slow transport?

I want to set postfix to use a "slow" transport for a particular site, because this site has limited a low rate for mail delivery, I did this:

Code:

# vi /etc/postfix/master.cf

smtp      unix  -      -      n      -      15      smtp

# When relaying mail as backup MX, disable fallback_relay to avoid MX loops

relay    unix  -      -      n      -      -      smtp

        -o fallback_relay=

slow      unix  -      -      n      -      1      smtp

        -o smtp_destination_concurrency_limit=1



# vi /etc/postfix/transport

163.com    slow:

thus there is only one slow transport, and 15 smtp transports. and mails to XXX@163.com should use the "slow" one.

But I still been rejected by that site from about 14:00 to about 20:00 every day(The busy moment of a day):
554 sender is reject: 0, mx4, ...(in reply to MAIL FROM command)

Before, when I didn't set default_process_limit=16, I got "IP is rejected" or "IP is hungup" from the mail server of that site and the mails were deferred. So I limit the process number, at first it's OK because there are many deferred mails in the queue, but now, after the deferred mails all have been delivered, some mails are bounced(in the time mentioned below), so I want to use slow transport, but it seems that there is no effect. why?

Does the slow transport setting take effect? How can I know? how can I make sure the mails to XXX@163.com does only use the very "slow" transport--I haven't found "slow" word from maillog?

Some other parameters I have changed:

Code:

initial_destination_concurrency = 1

default_destination_concurrency_limit = 1

smtp_destination_concurrency_limit = 4

default_destination_recipient_limit = 2

smtp_connection_cache_reuse_limit = 2

smtp_connection_cache_time_limit = 1s

smtp_connection_cache_on_demand = no

# smtp_connection_cache_destinations = 163.com



in_flow_delay = 4s



maximal_queue_lifetime = 6d

qmgr_message_recipient_limit = 1000

qmgr_message_active_limit = 800

default_recipient_limit = 100



queue_run_delay = 2000s

minimal_backoff_time = 2000s

maximal_backoff_time = 6000s



# smtpd_recipient_limit = 100



transport_maps = hash:/etc/postfix/transport

alias_database = hash:/etc/postfix/aliases

alias_maps = hash:/etc/postfix/aliases

Thanks.