On the same subject, I have this issue with someone who is using a .solutions email address. Adding that TLD to the allowed domains in the mailformatting_php.php file works fine, BUT whenever I add a new email behavior or update an existing one, that file is updated automatically and my changes are removed. This means I always have to remember to manually add that TLD back in.
Commenting out the lines to prevent checking sounds like a great idea, however would the same thing happen i.e. the change would be overwritten whenever an update is made? Is there any way to prevent this?