Alan,
Mail adresses are to be seperated by comma (,).
yang,
I had a quite similar problem with sending alerts/logs to my yahoo e-mail address. The mail didn't came through due to a change in yahoo's spammail blocking system. It took several weeks until the mails started to came through again. I figured out that the problem was related to the filter by studying the mail delivery error messages, that were sent back to the mail provider, that I'm using for alert and log sending.
Ingo