Automatic Message on User Registration

Probably a long shot, but I have Ultimate Member installed alongside this plugin, and I was wondering if it would be possible to automatically send new users a predefined message from a specific admin user when they register on the website. Something like, “Thanks for joining our site! Let us know if you have any questions by replying to this message”.

I have conversation starting limited to admins only, so subscribers can’t message anyone on their own. If I could automate the initial message from the admin that would be a yuuuge help.