Well since you are at one location trying to go through your ISP to send Email (SMTP) might be the problem. Most ISPs block port 25 beyond their own servers in a vain attempt to slow SPAM. So if you using Mail, go to Mail's Preferences and in the Accounts tab follow these steps:
1. Highlight your Account for the email server.
2. Near the bottom of the pane you will see "Outgoing Mail server (SMTP):" with a pull down to edit you SMTP server settings. Plus it down to you hosting services' SMTP server (to edit a pop up will come down, highlight your server's SMTP settings.
3. When the server is highlighted in the right hand pane click on the "Advanced" tab and follow your hosting servers instructions to use or not se SSL and to select the correct SMTP port.
Now if it still doesn't send the email in Mail go to the menu item "Window" and open the "Connection Doctor" to see if Mail gives you are error connecting to the Hosting Service's SMTP server, to try determine the problem.