I've had over 150,000 people sign up through my server and only today I've encountered my first email address with an apostrophe.
I always thought that email@example.com
was invalid. And many of the filters and tests that you run come back showing that is invalid.
But in doing some research about the "technically" allowed characters all indications show that to be a valid. (see wikipedia article).
So is this one of those things that is "on the books" that it is technically okay but in reality no one does it. Gmail doesn't allow it, an online test tool like this doesn't allow it (http://verify-email.org/
So my question is, what's the practical reality. Although permissible, does anybody really do it? I had my first one in over 150,000 entries. Is that how rare it is?
Thanks for any insight you can give.