Cannot register, always get: The e-mail address is invalid (General)
The solution for me was to either make that code change or to revert the version of php on the server to 7.2 or lower.
I will add this information to the release page. Thank you for your investigation.
Sorry for nagging:
last time I've changed the PHP version, mlf could not connect to the SQL database (I got an error so I had to reinstall the forum).
So now I want to try to switch back the PHP version from 5.6 to 7.2: are there any specific rules that I must follow? (I know nothing about PHP).
Thank you, shian.