Try Sigsync(www.sigsync.com) Office 365 email Signature, Its server side email signature. You can configure it once, you will have a consistent, tamperproof email signature for all your users. It grabs all of the user data from our Active Directory. You can use it for branding, advertising, and disclaimers.
It is very reliable and easy to use, I find that from a signature customization perspective, Sigsync is far the best. I've been able to set up a single signature for an entire organization. If your comfortable making the signatures in HTML I would recommend that.