[SOLVED] NDR message on message failure

[snake_eyes]

okay, I will go ahead and set the value for 5 minutes so it supposed to be

maximal_queue_lifetime = 5m

is that right? if no please fix it by providing the correct comand

[snake_eyes]

I test it and I received the NDR "Much appreciated", but the content of the NDR is as below:

This is the mail system at host mail.najdschools.edu.sa.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

my question is how do I update this phrase "For further assistance, please send mail to postmaster." I wanna change the postmaster to siteadmin@example.com how to do it?

[snake_eyes]

Any updates gentleman ?