I can't seem to e-mail anyone with a YAHOO e-mail address unless I use a Gmail account. My Gmail account has nothing to do with CathInfo, however, so I'm hesitant to use it all the time.
But CathInfo, as well as any other domains on that webhosting account, gets automatically rejected if I try to e-mail anyone on Yahoo.com. It's quite annoying.
This will also affect things like password reset and system activation. CathInfo.com itself can't contact a Yahoo.com e-mail. And unlike myself, it HAS no other options. The website itself can ONLY come from CathInfo. The webserver can't magically use a Gmail account to send system messages from.
Long story short -- try to avoid Yahoo.com e-mail addresses, at least on CathInfo.