The Powershell-based Outlook signature solution provided in this blog post was created because I was unable to find any other solutions that met my expectations.
The only script that came close to my needs was the one provided by Jan Egil: http://gallery.technet.microsoft.com/office/6f7eee4b-1f42-499e-ae59-1aceb26100de, but it returned quite a few errors, was missing some functions I needed, but also had other functions, that was not needed in my case.
Note that the script was last updated in 2014, and I currently have no plans for updating it (as of 2019-09-16). It has not been tested on Outlook versions following Office 2013.
The Outlook signature script solution
This script will gather information from Active Directory and automatically populate the fields in the signature.
Here is my script, and thanks again to Jan Egil for providing the original functionality 🙂
Download: TechNet Gallery