Hi @QwertyMash,
I see that your powershell script has had great success for some. We have had a VBS script in place that used to work for our Outlook desktop clients, that was created by a former employee. Lately it has been very hit and miss in applying, and has also stopped running silently, and we can't figure out why. So that lead me to seek out better alternatives, and finding yours. I like the idea of getting ours to work like yours and if it could work on OWA. Let me know if ours could easily be converted to work in your .ps1 script format? Attached is what our completed signature looks like, but we also have it grab and display a 2nd address for user's that manage 2 locations. SignatureScriptv14.vbs