Hi Jilld,
To understand the issue correctly, are you referring to creating a signature on mobile device using the Fill & Sign app and transferring the same signature/initials to desktop via email or other way?
This is possible to get the signature synced across other devices and web, but for that you don't need to email it to yourself.
Follow the exact same instructions shared in the help document- Capture your signature on mobile and use it everywhere and you would be able to sync the signature across the desktop, the web, and all mobile apps, that you have created on mobile app using Fill & Sign.
Hope this is what you were looking for.
Regards,
Akanchha