These instructions are for Mac OS X 10.9, 10.8, 10.7, and 10.6.
Use the following instructions to configure your email program to use an alternate port for outgoing email. This is generally needed when your Internet provider blocks Port 25 from non-local servers (a common spam-prevention practice).
Mac OS X Mail
- Open Mail. In the menu bar, choose Mail -> Preferences, and then click Accounts.
- From the Accounts list, select your account, and then click the Account Information tab.From the Outgoing Mail Server drop down menu, choose Edit SMTP Server List.
- From the list of servers, select your server and then click the Advanced tab.Select “Use custom port” and in the space provided, enter 587.
- Close the Account Settings window, and then click Save in the message that appears.
- Open Thunderbird. In the menu bar, choose Tools -> Account Settings.
- In the left-hand pane, select Outgoing Server (SMTP).In the right-hand pane, select your server and click the Edit button.
- In the Settings section, change the number in the Port field to 587.