How to Add or Change an SMTP Server
Several popular email providers, including Google, Yahoo, Exchange, and AOL, are preconfigured with a default SMTP server on Macs. That isn’t the case with all email providers. You may never need to make a change to the default email server listed for an account, but you may be asked by an ISP or an employer to use a preferred SMTP server. To set a preferred outgoing SMTP mail server for an account in the Mail app:
Obtaining SMTP Server Information
Don’t stop at setting up your iCloud email account. Take the time to set up any other email providers in the Mail application so you can access them all from within the Mail app. In addition to the preconfigured email providers, you may have email providers that you enter manually under Add Other Account in Apple Mail. In this case, you must input all the provider’s information, including the SMTP server. Contact the email provider for the necessary information you need.