areed your “From” e-mail address is wrong, when you are using the default mail driver, you cannot fabricate your own e-mail address in the “From” field. You have to use the noreply+yourforumtag@freeflarum.com format.
I have fixed it for you, so e-mail delivery should work on your forum again (so this should fix both issues, since both were caused by e-mails not being sent properly)