MacOS Mail: How to Specify the Default Account

The Mail application on Mac computers can be configured to send and receive email from all your other email accounts in addition to your Mac Mail account. You might configure a Gmail, Yahoo, AOL, Outlook, or another email account to deliver the mail to those addresses to your Mac Mail app. When you reply to one of them, your reply uses the email address the sender used to contact you.

When you send a new email, you can send it from any of the accounts you access in Mail. Just click on the From field of any new message and choose the email address you want for the email from the drop-down menu.

If you use one of your accounts more frequently than the others, make that account email address the default From address on all your new emails. You can always change it manually on a case-by-case basis.

Information in this article applies to Macs running macOS Catalina (10.15), macOS Mojave (10.14), macOS High Sierra (10.13), or macOS Sierra (10.12).

How to Specify a Default Account in macOS Mail

Your Mac Mail account may already have one of your Apple email addresses listed as the default. To change it and specify a new default email account in Mac Mail:

Open the Mail application on your Mac and select Mail > Preferences from the menu bar.
Click the Composing tab at the top of the Composing preferences window that opens.
Select the desired account from the drop-down menu next to Send new messages from.
As an alternative, select Automatically select best account at the top of the drop-down menu next to Send new messages from to instruct Mail to select the best address for an email based on the mailbox you are using. For example, if you are sending an email from your Gmail account, Mail selects a Gmail address for the From field.
Close the preferences window to save the change.