.NET Email Regex

generator.cs

var crlf = @"(\r\n)";
var wsp = @"[ \t]";
var vchar = @"[\u0021-\u007e]";
var obsNoWsCtl = @"[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f]";
var commentText = @"([\u0021-\u0027\u002a-\u005b\u005d-\u007e]|" + obsNoWsCtl + ")";
var quotedPair = @"\\(" + vchar + "|" + wsp + @"|[\r\n\0]|" + obsNoWsCtl + ")";
var quotedText = @"([\u0021\u0023-\u005b\u005d-\u007e]|"+obsNoWsCtl+")";
var domainText = "([\u0021-\u005A\u005e-\u007e]|" + obsNoWsCtl + ")";
var atomText = "[a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]";
var fws = "(" + wsp + "+" + "(" + crlf + wsp + "+)?|(" + crlf + wsp + "+)+)";   
var comment = @"(\((((?'paren'\()|(?'-paren'\))|"+commentText+"|"+fws+"|"+quotedPair+@")*(?(paren)(?!)))\))";
var cfws = "(" + comment + "|" + fws + ")*";
var atom = "(" + atomText + "+)";
var quotedContent = "(" + quotedText + "|" + quotedPair + ")";
var quotedString = "(\"(" + fws +"?" + quotedContent + ")*" + fws + "?\")";
var dottedAtoms1 = "(" + cfws + "?(" + atom + "|" + quotedString + ")"  + cfws + "?)";
var dottedAtoms = "(" + dottedAtoms1 + @"(\." + dottedAtoms1 + ")*)";
var localPart = "(?'localPart'" + dottedAtoms + ")";
var domainLiteral = "(" + cfws + @"?\[(" + fws + "?" + domainText + ")*" + fws + @"?\]" + cfws +"?)";
var domain = "(?'domain'" + dottedAtoms + "|" + domainLiteral + ")";
var email = "^" + localPart + "@" + domain + @"\z";
 
// Console.WriteLine(email);
 
var valid = @"I.                        
 am.                  
 a.      
 nice.
 guy@(yeah)you.com";
 
var success = Regex.Match(valid, email, RegexOptions.ExplicitCapture|RegexOptions.Singleline);
Console.WriteLine("Parsed: {0} <@> {1}", success.Groups["localPart"], success.Groups["domain"]);

output

^(?'localPart'((((\((((?'paren'\()|(?'-paren'\))|([\u0021-\u0027\u002a-\u005b\u
005d-\u007e]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f])|([ \t]+((\r\n)[ \t
]+)?|((\r\n)[ \t]+)+)|\\([\u0021-\u007e]|[ \t]|[\r\n\0]|[\u0001-\u0008\u000b\u0
00c\u000e-\u001f\u007f]))*(?(paren)(?!)))\))|([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t
]+)+))*?(([a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+)|("(([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \
t]+)+)?(([\u0021\u0023-\u005b\u005d-\u007e]|[\u0001-\u0008\u000b\u000c\u000e-\u
001f\u007f])|\\([\u0021-\u007e]|[ \t]|[\r\n\0]|[\u0001-\u0008\u000b\u000c\u000e
-\u001f\u007f])))*([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+)?"))((\((((?'paren'\()
|(?'-paren'\))|([\u0021-\u0027\u002a-\u005b\u005d-\u007e]|[\u0001-\u0008\u000b\
u000c\u000e-\u001f\u007f])|([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+)|\\([\u0021-\
u007e]|[ \t]|[\r\n\0]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f]))*(?(paren
)(?!)))\))|([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+))*?)(\.(((\((((?'paren'\()|(?
'-paren'\))|([\u0021-\u0027\u002a-\u005b\u005d-\u007e]|[\u0001-\u0008\u000b\u00
0c\u000e-\u001f\u007f])|([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+)|\\([\u0021-\u00
7e]|[ \t]|[\r\n\0]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f]))*(?(paren)(?
!)))\))|([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+))*?(([a-zA-Z0-9!#$%&'*+/=?^_`{|}
~-]+)|("(([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+)?(([\u0021\u0023-\u005b\u005d-\
u007e]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f])|\\([\u0021-\u007e]|[ \t]
|[\r\n\0]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f])))*([ \t]+((\r\n)[ \t]
+)?|((\r\n)[ \t]+)+)?"))((\((((?'paren'\()|(?'-paren'\))|([\u0021-\u0027\u002a-
\u005b\u005d-\u007e]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f])|([ \t]+((\
r\n)[ \t]+)?|((\r\n)[\t]+)+)|\\([\u0021-\u007e]|[ \t]|[\r\n\0]|[\u0001-\u0008\u
000b\u000c\u000e-\u001f\u007f]))*(?(paren)(?!)))\))|([ \t]+((\r\n)[ \t]+)?|((\r
\n)[ \t]+)+))*?))*))@(?'domain'((((\((((?'paren'\()|(?'-paren'\))|([\u0021-\u00
27\u002a-\u005b\u005d-\u007e]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f])|(
[ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+)|\\([\u0021-\u007e]|[ \t]|[\r\n\0]|[\u000
1-\u0008\u000b\u000c\u000e-\u001f\u007f]))*(?(paren)(?!)))\))|([ \t]+((\r\n)[ \
t]+)?|((\r\n)[ \t]+)+))*?(([a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+)|("(([ \t]+((\r\n)[ 
\t]+)?|((\r\n)[ \t]+)+)?(([\u0021\u0023-\u005b\u005d-\u007e]|[\u0001-\u0008\u00
0b\u000c\u000e-\u001f\u007f])|\\([\u0021-\u007e]|[ \t]|[\r\n\0]|[\u0001-\u0008\
u000b\u000c\u000e-\u001f\u007f])))*([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+)?"))(
(\((((?'paren'\()|(?'-paren'\))|([\u0021-\u0027\u002a-\u005b\u005d-\u007e]|[\u0
001-\u0008\u000b\u000c\u000e-\u001f\u007f])|([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]
+)+)|\\([\u0021-\u007e]|[ \t]|[\r\n\0]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\
u007f]))*(?(paren)(?!)))\))|([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+))*?)(\.(((\(
(((?'paren'\()|(?'-paren'\))|([\u0021-\u0027\u002a-\u005b\u005d-\u007e]|[\u0001
-\u0008\u000b\u000c\u000e-\u001f\u007f])|([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+
)|\\([\u0021-\u007e]|[ \t]|[\r\n\0]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u00
7f]))*(?(paren)(?!)))\))|([ \t]+((\r\n)[ \t]+)?|((\r\n)[\t]+)+))*?(([a-zA-Z0-9!
#$%&'*+/=?^_`{|}~-]+)|("(([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+)?(([\u0021\u002
3-\u005b\u005d-\u007e]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f])|\\([\u00
21-\u007e]|[ \t]|[\r\n\0]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f])))*([ 
\t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+)?"))((\((((?'paren'\()|(?'-paren'\))|([\u00
21-\u0027\u002a-\u005b\u005d-\u007e]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u0
07f])|([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+)|\\([\u0021-\u007e]|[ \t]|[\r\n\0]
|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f]))*(?(paren)(?!)))\))|([ \t]+((\
r\n)[ \t]+)?|((\r\n)[ \t]+)+))*?))*)|(((\((((?'paren'\()|(?'-paren'\))|([\u0021
-\u0027\u002a-\u005b\u005d-\u007e]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007
f])|([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+)|\\([\u0021-\u007e]|[ \t]|[\r\n\0]|[
\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f]))*(?(paren)(?!)))\))|([ \t]+((\r\
n)[ \t]+)?|((\r\n)[ \t]+)+))*?\[(([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t]+)+)?([!-Z^
-~]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f]))*([ \t]+((\r\n)[ \t]+)?|((\
r\n)[ \t]+)+)?\]((\((((?'paren'\()|(?'-paren'\))|([\u0021-\u0027\u002a-\u005b\u
005d-\u007e]|[\u0001-\u0008\u000b\u000c\u000e-\u001f\u007f])|([ \t]+((\r\n)[ \t
]+)?|((\r\n)[ \t]+)+)|\\([\u0021-\u007e]|[ \t]|[\r\n\0]|[\u0001-\u0008\u000b\u0
00c\u000e-\u001f\u007f]))*(?(paren)(?!)))\))|([ \t]+((\r\n)[ \t]+)?|((\r\n)[ \t
]+)+))*?))\z