RFC822: email address validation with regular expressions

Question

as you know, this is how we validate an email address:

(?:(?:\\r\\n)?[ \\t])*(?:(?:(?:[^()<>@,;:\\\\\".\\[\\] \\000-\\031]+(?:(?:(?:\\r\\n)?[ \\t]
)+|\         


        

Answer 1

can you please explain to me what is going on here?

Get hold of the first (or maybe the second, I know it isn't in the third) edition of "Mastering Regular Expressions". This works through the RFC defining valid email addresses, and builds the regex needed.