Copy the existing signature from the following location of the user :
C:\Users\your_username\AppData\Roaming\Microsoft\Signatures
Open the signature html file with notepad, wordpad, or another text editing program
- Copy all of the contents of the signature (as is don't change anything) and send it as an email.
- Copy the contents of the email
- Go to settings (cog icon) within the outlook app. Select signatures and then copy the contents into the field (make sure of no spaces as that can mess up the formatting of the signature)
- The html signature should now show properly when creating emails within the mobile verison of outlook.