Are apostrophes valid in an email address?

[Rev Simon Rumble]

On 15/2/2006, "Lusercop" <`the.lusercop'@lusercop.net> wrote:

>I have enough trouble using "+" as a separator
>for clueless web forms.

Which is why I swapped from Postfix's default of "+" to "." years
ago.  Too many clueless web forms.