Follow the steps below to add your personal signature to all emails sent from your email account:
Step 1: Go to the Settings --> team settings page in your account and goto Email Accounts section
Step 2: Click on the email account, or on the settings button corresponding to the account you wish to set the signature.
Step 3: Click on Add / Edit Signature
Step 4: Type your desired signature for the account. If you want to add your html code add it as shown in the img below: