I used to have trouble sending mail from some hotel networks and this is how I fixed it...it now works everywhere it used to and everywhere it didn't.
Go to mail preferences. Select accounts and and the account information tab. At the bottom is the Outgoing mail server list. If you hit the scroll arrow the last option is " edit server list"...select that. Then you will be at a box where you can select SSL and change port to 587.
Hope it works for you.