Applescript and Mail in macOS Sierra: broken feature?

Question

I guess you can't make a signature in Mail using AppleScript anymore?

If you're running Sierra, give this simple script a try:

tell application "Mail" to make new signature with properties {name:"My Signature"}

All I get is "Mail got an error. AppleEvent handler failed."

Is this a bug?

Answer 1

It appears that the "AppleEvent handler failed" error occurs on many other occasions when running AppleScript on MacOs Sierra. I cannot delete mailboxes for instance: applescript can't delete any mailbox