Send fresh email from Gmail alias

Use email aliases in Mail on Mac

An email alias is like a nickname and helps to keep your actual email address private. When you send emails using an alias, your recipients never see your actual email address.

Create or change an alias

1. In the Mail app  on your Mac, choose Mail > Preferences, then click Accounts.
2. Select an account, then click Account Information.
3. Click the Email Address pop-up menu, choose Edit Email Addresses, then do one of the following:

• • Add an alias: Click the Add button , then enter a name and email address.
  • Edit an alias: Click the Full Name or Email Address field, then change the name or email address.
  • Remove an alias: Select an alias, then click the Remove button .

Send an email from an alias

1. In the Mail app  on your Mac, move the pointer over the From field in a message you’re writing.
2. Click the pop-up menu that appears, then choose an email alias.

https://support.apple.com/guide/mail/use-email-aliases-mlhlp1205/mac

In the Compose window have her click on the From: field, do those Alias choices show there?

Thanks LOL didn't know if Aliases showed up there or not, now I know LOL.