Comment 12 for bug 1615280

The older version of phpmailer in 15.10_STABLE and 15.04_STABLE doesn't validate email addresses tightly enough. Since this is only a medium-priority bug, I'm going to kill the backport to those versions.

Anyone who's interested in fixing this for 15.04 or 15.10 yourself, you could probably start with my 15.04 patch, which centralizes all the email validation into the "sanitize_email()" function in htdocs/lib/mahar.php. Then just change the implementation of sanitize_email() to something that works for you, perhaps a regex or FILTER_VALIDATE_EMAIL.