In outlook the mail server settings are configured from the following menu picks:

• Tools> Accounts> Mail

Select the account you are having problems sending with, then click "Properties". There you will see 4 tabs at the top of the window that opens up. They are "General, Servers, Connection, Advanced".

The server tab controls where the SMTP server is set. The advanced tab is where you can change the port to 587 for Outgoing Mail (SMTP).