It should be one of these:

bounce_queue_lifetime = 1d
maximal_queue_lifetime = 1d

Hi, Thanks for your quick answer.

I think it is

maximal_queue_lifetime = 1d

I got it from below URLs.

http://www.postfix.org/rate.html


maximal_queue_lifetime (default: 5 days): How long a message stays in the queue before it is sent back as undeliverable. Specify 0 for mail that should be returned immediately after the first unsuccessful delivery attempt