In OWA 2016 you can add images to a signature with Insert pictures inline option. In OWA go to Settings (gear sign) > Options > Mail > Email signature.
There's no such an option in OWA 2010 and OWA 2013. Follow the steps below to add an image to your signature in Outlook Web App 2010/2013.
Note: Entering HTML code does not work either since it is not automatically recognized.
Important: Mozilla Firefox and Internet Explorer were tested and proved to work well. The image should be accessible on the Web and have a URL which can be used to bring it up in a browser. Pictures added from Google Chrome may not be shown properly in the signature, as Chrome encodes the images differently.
- Open the image you want to add in a browser window (Internet Explorer is used in the example).
- Right-click the image and choose Copy.
- Open OWA and go to Options > Settings > Mail to edit your signature.
- Use Ctrl+V to paste the image you copied since context menu is not available. Check the box for automatic signature addition if needed.
automaticaddition is disabled, add your signature to a new message using Insert > Your Signature.