2. Open the preferences under the mail menu.
3. Open the Settings window and click Signature.
4. The first column is the list of email accounts, the second column is the list of signature names corresponding to the current email account, and the third column is the current signature content.
5. Click+to create a new signature,-delete the current signature. You can directly superimpose the signature title and directly enter the signature content in the third column.
6. Set the default display signature when creating a new e-mail in the selected signature list.
7. You can choose different signatures according to the actual situation.
Advice from macz, I hope it will help you!