Mailx Not sending

How can I check to see how/why my mailx program is not sending?

/var has enough room.

-Thanks

---------- Post updated at 08:48 AM ---------- Previous update was at 08:35 AM ----------

I tested the mailx to send with this command:

echo "This is going to be body of the mail" |mailx -s "FOR TESTING" "abvc@xyz.edu"

And it works. But my scheduled mail is not working.

can you provide your scheduled mailx? how are have you scheduled? is it a cronjob?