Are special characters possible in the email address?

Question

I use the Apache Commons email validator and refuse to accept an email address, for example:

ąźóęł@email.com 

so I would like to ask if it’s not right to allow them, or should I change the validator?

Answer 1

http://en.wikipedia.org/wiki/E-mail_address#RFC_specification contains all the necessary information: a link to the official RFC specifications, whose characters are good, etc.