What characters are allowed in an email address?

Question

I\'m not asking about full email validation.

I just want to know what are allowed characters in user-name and server parts of email address

Answer 1

Google do an interesting thing with their gmail.com addresses. gmail.com addresses allow only letters (a-z), numbers, and periods(which are ignored).

e.g., pikachu@gmail.com is the same as pi.kachu@gmail.com, and both email addresses will be sent to the same mailbox. PIKACHU@gmail.com is also delivered to the same mailbox.

So to answer the question, sometimes it depends on the implementer on how much of the RFC standards they want to follow. Google's gmail.com address style is compatible with the standards. They do it that way to avoid confusion where different people would take similar email addresses e.g.

*** gmail.com accepting rules ***
d.oy.smith@gmail.com   (accepted)
d_oy_smith@gmail.com   (bounce and account can never be created)
doysmith@gmail.com     (accepted)
D.Oy'Smith@gmail.com   (bounce and account can never be created)

The wikipedia link is a good reference on what email addresses generally allow. http://en.wikipedia.org/wiki/Email_address