Open your HTML email signature file in your Firefox browser.
Press Ctrl + A (Cmd + A for Mac) to select the entire email signature, then press Ctrl + C (Cmd + C for Mac) to copy it.
IMPORTANT: Do not use your mouse to select the area, only use Ctrl + A as you may miss out on grabbing some of the code.
Open Outlook in your Firefox web browser and click the Settings icon at the top right of your screen. Select Account, then Signatures from the left menus.
Click the New Signature button and enter a name for your email signature. Click inside the text box below, then press Ctrl + V (Cmd + V for Mac) to paste your copied email signature.
Under Select Default Signatures, select your signature name for New Messages and Replies/Forwards. Hit Save.
Create professional email signatures that make a lasting impression. Easy to customize, always looks perfect across all email clients.
Outlook on the Web 365 Email SignaturesClose out of your settings and compose a new email. Your email signature will now automatically insert.
Install the latest version of the Firefox Add-On here. Click Continue to Installation when prompted, then Add.
Open the Email Signature Rescue add-on by clicking the puzzle icon, then selecting Email Signature Rescue.
Click the Add New Email Signature button to create an install. Select your email client from the dropdown list, then paste your signature key into the next field and click Save Key.
Important: If you're using more than one email account, click Advanced Settings then enter the email address of the account that you want your email signature to work with. This will prevent the signature from being applied to all email accounts.
Compose a new email and your email signature will automatically insert when sending an email from Outlook from your Firefox browser.