/// <summary>
/// Checks whether the provided e-mail address is in a valid format (as specified by RFC 822).
/// </summary>
/// <param name="emailAddress">The e-mail address to check.</param>
/// <returns>True if valid, otherwise false.</returns>
public static bool CheckEmailValid(string emailAddress) {
	// Code by Jeremy Morton, 2010-09-30
	// If e-mail address validity check fails, tell user... Invalid e-mail address format (Must be similar to user@domain.com)

	// Remember: .* is greedy by default!
	string reEmailAddressPattern = @"
		^			# RFC 822 says e-mail addys consist of any CHAR except specials, SPACE and CTLs.
					# We also have the @ and . to seperate user or hostnames.
					# CHAR is ASCII 0-127(0x00-7F).  SPACE is ASCII 32(0x20).
					# CTLs are ASCII 0-31(0x00-1F) and 127(0x7F).  Specials are ( ) < > @ , ; : \ "" . [ ]
					# ASCII 127(0x7F) is a DEL control character - prudent to disallow this in an e-mail address.
		[^\x7F\x80-\xFF\x00-\x20\(\)\<\>\@\,\;\:\\\""\[\]]+
					# ^ Username... even '(.)@host.com' is ok.
		\@
					# ^ @
		[^\x7F\x80-\xFF\x00-\x20\(\)\<\>\@\,\;\:\\\""\[\]\.]+
					# ^ Host part 1 (no dots yet): 'blah@(host).com.com'.
		\.
					# ^ .
		[^\x7F\x80-\xFF\x00-\x20\(\)\<\>\@\,\;\:\\\""\[\]\.]+
		[^\x7F\x80-\xFF\x00-\x20\(\)\<\>\@\,\;\:\\\""\[\]]*
					# ^ Host part 2 (remaining dots allowed): 'blah@host.(com.com)'.
		$
	";

	Regex reEmailAddress = new Regex(reEmailAddressPattern, RegexOptions.IgnorePatternWhitespace);
	return reEmailAddress.IsMatch(emailAddress);
}