Steps to reproduce the issue

Create yourself some test users:

I note after that "Receive System Emails" is set to OFF by default. I left it off.

Go to Admin -> Users -> Mass Mail Users

Compose an email

Leave settings on the right alone as:

Click Send Email

Expected result

Edit: 3 emails are sent to the three registered users (as configured above) = They have Receive System Emails = Off so they dont get the email, I guess that's correct.

Edit: However on further testing, regardless of the users Receive System Emails setting, they never get the mass email

Therefore I expect that Joomla would say that 1 email has been sent.

Actual result

Joomla 4 tells me it has sent 3 emails.

HOWEVER it has in fact only sent ONE EMAIL and that email was actually sent to THE SUPER ADMINS EMAIL ADDRESS and not to any of the registered users.

System information (as much as possible)

Using MailHog for catching emails sent by SMTP to a different docker container. MailHog is rock solid and receives all emails that Joomla sends.

Additional comments

BONUS, even if Receive System Emails is enabled, Joomla 4 still only sends ONE email and not 3 or 4 emails as expected.