Apostrophe not allowed in local-part of email address

[johndeery]

Currently, WP will not allow an apostrophe character in the local-part of an email addresss, so someone with an email like john.o'connor@… will not be allowed.

According to RFC 2822, however:

...the local-part of the e-mail may use any of these ASCII characters:

• Uppercase and lowercase letters

• The digits 0 through 9

• The characters,! # $ % & ' * + - / =? _ ` { ¦ } ~

• The character "." provided that it is not the first or last character in the local-part.

Originally posted in the MU trac system, was requested to be posted here, so if it has already been resolved, I apologize.

Should be part of #4616.

duplicate of #4616