Delivering to strictly policied servers

Oymakoon · *nix forums beginner Joined: 18 Mar 2008 Posts: 2

There is a remote server with 500+ users subscribed to my mailing list. Recently admins of that server imposed some strict policies and mail for those subscribers is now in deferred queue for most of the time.

Policies are as follows:
1. No more than 1 connection from one IP address
2. Sequential reconnect after connection terminated or lost is allowed not sooner than 5 minutes.

One IP-one connection issue was resolved by adding separate transport just for this destination. And limiting that transport to maxproc = 1 in master.cf.

Now I am stuck with #2 - how to back off after first error and do not try to reconnect in 5 minutes? And how to send a batch of say 100 messages in one smtp session?

Google