Sometimes the mail system will send you notification that your mail
could not be delivered. When that happens, don't just resend the note;
try to find out what the problem was. You may have put the wrong
address on the message, or a gateway between mail systems might be
down, or the other person's mail system might be down, or there might
be a problem with your own mail system. Here's what to do:
Ask around and find out whether your colleagues are having problems with your local mail system. If the answer is no,
Call the other person and check whether you used the right email
address.
If you used the correct address, ask whether they've been having
email problems.
If it turns out that you used the wrong address, you can just resend the
message using the right one. If there's a mail system problem, or if you
can't figure out what the problem is, you'll have to resend the message
later or figure out alternative means of transferring the information.