Recipient verification delay

[Daniel L. Miller]

I've been using recipient verification for some time with good results 
but I think I need to make an adjustment to accommodate the changing 
email world.  It appears a number of servers have adopted minimal 
greylisting - such that they immediately reject initial contacts but 
have a minimal timeout (just a few seconds) before accepting.

At the moment, my client behavior (Thunderbird) on a send is to show 
processing...for an extended period.  However, if after sending - and 
seeing the apparent timeout condition - the user cancels the send and 
then manually retries it immediately goes out.  So my belief is my 
Postfix server is performing one or more verification attempts within 
the remote greylisting servers block - and is then waiting for responses.

How can I set Postfix to make an initial attempt, not wait longer than 2 
seconds for a response, and then make another perhaps 5 or 10 seconds later?
--
Daniel