For Office 365 Browser App, you can add your email signature automatically via this link or follow the steps below to add your signature:
- In a web browser, sign in to Outlook Web App. Enter your username and password, and then select Sign in.
- On the navigation bar, choose My account.
- On the navigation bar, choose Settings .
- Under Settings , choose Mail.
- Under Email signature, in the text box, paste your generated Email Signature text you want to use.
- If you want your signature to display at the bottom of all outgoing items, including replies and forwards, select Automatically include my signature on messages I send. If you don’t select this option, you can manually add your signature to any message.
- Choose Save.