Add timeouts to outgoing SMTP mail

I wasn't able to test if this actually fixes the problem we're running into since it's hard to simulate an unresponsive SMTP server. At the very least, these timeouts seem reasonable and shouldn't hurt anything except very slow SMTP servers.
This seems too long. After 60s I (as a user) am likely to have decided that the app is dead and reset it. I'm likely to be patient for 15s, though.