Post-account creation message

I run a Mattermost instance for an organization with strict security requirements, and must add new members to our team manually. I want to tell each new user to contact me so that I can add them to our team (I can see the emails of those who should join using a separate platform).

Is there a way to show a message after a user creates their account?

Could something like this work GitHub - mattermost/mattermost-plugin-welcomebot?

With our current confirmation, no, but thanks for suggesting.

On our Mattermost instance, accounts may be freely created, but an admin will have to manually add each user to our team as a security measure. After clicking “Create account”, they won’t see any teams to join.

I’d like to show a message saying to email someone once their account has been created, or have some kind of automated task to email me once an account is created.

I did this long ago by editing the JS that tells you “There are no teams available to join.” but it was lost after an upgrade.