Cox Webmail

I'm new to using Cox Webmail. :--(  Do you know that if you send an email and make a mistake in the address that Cox doesn't tell you they can't send it nor does Cox send it back to you.  After waiting days for several replies, I called the addressees to find out why they didn't answer my emails and was informed they didn't receive them.  Then, when I talked to three different Cox reps, none had a clue that that was happening until they tried it themselves and then said they didn't know how to get it fixed.  That's a bit scary!  Has anyone else noticed this?