Steps

Make sure you have 2FA enabled on your gmail account

• For this method to work, you need to have two factor authentification enabled for your Google account. If it’s not, follow the link below and set it up.

• Enable 2FA for your Google account

• 

Create an App Password

• Google will verify your ownership with this app password. Select “Mail” under app, and “Mac” under device. Hit “Generate”. Copy and keep for later!

• Create an app password

Add your email to Gmail

• Go to Gmail -> Settings -> Accounts and Import. Then, select “Add another email address you own” under Aliases.

• 

Fill in your sender’s information

• Set your forwarded email (your alias) and your sender’s name. Untick “treat as an alias”.

• 

Fill in your email information

• SMTP is smtp.gmail.com, port is right already.

• Username is your gmail address (incl. @gmail.com)

• Password is the password you generated on Step 2.

• Leave TLS enabled as is

Confirm ownership

• You will receive an email from GMail asking you to confirm ownership with a code. Fill in the code in the popup modal, and you are all set!

Send emails from your alias

• Now you can just select your alias in the list when you compose a new message.