a ‘+’ symbol is a valid part of an email username, and can be used in debugging and SPAM control. I use firstname.lastname@example.org (the real address being email@example.com) when I post my email on a site where it could get displayed for spam harvesters.
However, most CMSs use this regular expression in their email address checking algorithms.
Please replace that line with this so the plus sign gets recognized. That is a much better practice. Thank you!
Another option from Phil :
I’ve always used these two in conjunction. The first one we don’t want, and the second one we do want.