Where is the "badmail" kinda folder in rh 7.1?
 

A quick question,
Where does the bad mails go? into which folder?
Thanks.
Well, actually one more thing..
How can I set a mail to be sent to the badmail folder if the recipients in unavaible, so that it won't keep the spool folder busy.

Sendmail keeps its deferred mail in /var/spool/mqueue (IIRC), a queue that spans 5 days std (queuereturn). After 5 days itll send the mail back to the user with a warning message it can't be sent. All timeout functions are configurable in /etc/sendmail.cf: Timeout.queuereturn and Timeout.queuewarn.
Depending on your version of sendmail this may be chalked up as:
O Timeout.queuereturn=5d
O Timeout.queuewarn=4h
or
OT5d/4h
Queuewarn means a warning will be sent after the msg being in the queue for 4 hrs. Changing from 5 days to something too low isn't good, a mailserver could be down for just a day.
Don't forget to reload sendmail for the config to stick.

Got it.. thanks,
For this reloading issue,
What should be the reloading interval as in time??

PS:, we're currently mass mailing.. sending about 100.000 e-mails at a time.
Thank you.

Depends I think on whats the average.
I think it would be best to let it run, and have a daily/hourly "sendmail -bp | head -n 1 && sendmail -bp | grep "@" | gawk '{print $1}'", this will return the number of messages still in the queue, and the addresses its holding. Then decide to either delete from the queue or let it run for a few more hours depending on how many times you try to clean the queue (sendmail -q, IIRC).

great.. :)
Thank you unSpawn..