Add a signature to all the emails you compose or reply on Office 365

Step 1: Sign into your Outlook webmail

Step 2: Click on Settings gear icon on the top-right corner.

Step 3: Scroll down and click View all Outlook settings

Step 4: Navigate to Mail >> Compose and reply.

Step 5: Enter the signature or add an image in the Email signature area

Step 6: Check both the check boxes on the bottom of the signature area

Step 7: Click Save