What kind of email server/account are you trying to use? I mean if you are using an smtp server on localhost, it may be accepting the relay from the web app and thus throws no errors but when it tries to send it is blocked at the firewall.
I test using a yahoo email address, I got my domain via yahoo domains and they provide email via bizmail.yahoo.com as the smtp server and that is what I use for testing. localhost smtp may be masking the real problem.
Hope it helps,
Joe