Set NewMessageSignature with Powershell without using Word

Question

So far, the only way I've found to change the default New Message Signature in Outlook is by instantiating Word:

$MSWord = New-Object -COMObject word.application 
$MSWord.EmailOptions.EmailSignature.NewMessageSignature="New Default"
$MSWord.Quit()

I don't fully understand what this snippet is doing, but it works.

The script is run at user Logon with a GPO, and results in Outlook's login prompt appearing for a few seconds while the value is being updated.

Is there a way to update this value without the user seeing a login prompt?

Edit: This page lists several ways to accomplish the task - I've opted for the registry edit route despite being advised it's not ideal. https://www.howto-outlook.com/howto/corporatesignatures.htm

Answer 1

If using Redemption (I am its author) is an option, it exposes Outlook signatures through the RDOSignatures object (returned from RDOSession.Signatures).