In the bottom left corner, select the little circle with your initials > Settings.

Step 2: Go to Mail > Smart Mail, then In the Email Greeting and Email Signature text boxes, enter any default text that you want to appear on all emails.

For Email Greeting, You can use any of the tags [honorific], [first name], [last name]. Entering any of these tags in the text boxes will automatically customize the tags according to the recipient of the email.

Step 4: Select Save Changes at the bottom of the page.