Has anyone seen an updated regex expression from Microsoft for the email
validation expression so that single quotes are allowed?

I've been using the canned regex for emails, but recently been informed by a
customer that the single quote is allowed as part of the email address (Mr.
O'Leary).

I prefer using the un-modified version from the framework, but will update
my local code regardless.

In article <u#9v5T01GHA.1***@TK2MSFTNGP06.phx.gbl>,
    Jim Dornbush <jdornb***@xrite.com> wrote:

In <11mv70vtf7i6***@corp.supernews.com>, I described a stopgap that
you might consider in a pinch.

The idea is to dump the regular expression from the Email::Address CPAN
module. Code below.

Moral: regular expressions are poor substitutes for parsers.

Enjoy,
Greg

using System;
using System.Text.RegularExpressions;

using NUnit.Framework;

namespace Application
{
  public interface SyntaxChecker
  {
    bool WellFormed(string input);
  }

  public class EmailAddressChecker : SyntaxChecker
  {
    // derivative of work with the following copyright and license:
    // Copyright (c) 2004 Casey West.  All rights reserved.
    // This module is free software; you can redistribute it and/or
    // modify it under the same terms as Perl itself.

    // see http://search.cpan.org/~cwest/Email-Address-1.80/

    #region dumped regular expression
    private static string gibberish = @"
    (?-xism:(?:(?-xism:(?-xism:(?-xism:(?-xism:(?-xism:(?-xism:\
    s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^
    \x0A\x0D]))|(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))
    s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^
    \x0A\x0D]))|(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))
    ?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|(?-xism:\s*\((?
    0D]))|)+)*\s*\)\s*))+)*\s*\)\s*)+|\s+)*<DQ>(?-xism:(?-xism:[
    ^\\<DQ>])|(?-xism:\\(?-xism:[^\x0A\x0D])))+<DQ>(?-xism:(?-xi
    sm:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xis
    m:[^\x0A\x0D]))|(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\
    ]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|)+)*\s*\)\s*))+)*\s*\)\
    s*)+|\s+)*))+)?(?-xism:(?-xism:(?-xism:\s*\((?:\s*(?-xism:(?
    -xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|(?-xism:
    \s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[
    ^\x0A\x0D]))|)+)*\s*\)\s*))+)*\s*\)\s*)+|\s+)*<(?-xism:(?-xi
    sm:(?-xism:(?-xism:(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^(
    )\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|(?-xism:\s*\((?:\s*(
    ?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))
    +)*)(?-xism:(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))
    (?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|)+)*\s
    *\)\s*))+)*\s*\)\s*)+|\s+)*)|(?-xism:(?-xism:(?-xism:\s*\((?
    0D]))|(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xi
    sm:\\(?-xism:[^\x0A\x0D]))|)+)*\s*\)\s*))+)*\s*\)\s*)+|\s+)*
    <DQ>(?-xism:(?-xism:[^\\<DQ>])|(?-xism:\\(?-xism:[^\x0A\x0D]
    )))+<DQ>(?-xism:(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\
    ]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|(?-xism:\s*\((?:\s*(?-x
    ism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|)+
    )*\s*\)\s*))+)*\s*\)\s*)+|\s+)*))\@(?-xism:(?-xism:(?-xism:(
    ?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?
    -xism:[^\x0A\x0D]))|(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^
    ()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|)+)*\s*\)\s*))+)*\s
    *\)\s*)+|\s+)*(?-xism:[^\x00-\x1F\x7F()<>\[\]:;@\,.<DQ>\s]+(
    ?:\.[^\x00-\x1F\x7F()<>\[\]:;@\,.<DQ>\s]+)*)(?-xism:(?-xism:
    \s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[
    ^\x0A\x0D]))|(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+)
    )|(?-xism:\\(?-xism:[^\x0A\x0D]))|)+)*\s*\)\s*))+)*\s*\)\s*)
    +|\s+)*)|(?-xism:(?-xism:(?-xism:\s*\((?:\s*(?-xism:(?-xism:
    (?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|(?-xism:\s*\((
    ?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\
    x0D]))|)+)*\s*\)\s*))+)*\s*\)\s*)+|\s+)*\[(?:\s*(?-xism:(?-x
    ism:[^\[\]\\])|(?-xism:\\(?-xism:[^\x0A\x0D])))+)*\s*\](?-xi
    sm:(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:
    \\(?-xism:[^\x0A\x0D]))|(?-xism:\s*\((?:\s*(?-xism:(?-xism:(
    ?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|)+)*\s*\)\s*))+
    )*\s*\)\s*)+|\s+)*)))>(?-xism:(?-xism:\s*\((?:\s*(?-xism:(?-
    xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|(?-xism:\
    s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^
    \x0A\x0D]))|)+)*\s*\)\s*))+)*\s*\)\s*)+|\s+)*))|(?-xism:(?-x
    ism:(?-xism:(?-xism:(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^
    ()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|(?-xism:\s*\((?:\s*
    (?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D])
    )|)+)*\s*\)\s*))+)*\s*\)\s*)+|\s+)*(?-xism:[^\x00-\x1F\x7F()
    <>\[\]:;@\,.<DQ>\s]+(?:\.[^\x00-\x1F\x7F()<>\[\]:;@\,.<DQ>\s
    ]+)*)(?-xism:(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+)
    )|(?-xism:\\(?-xism:[^\x0A\x0D]))|(?-xism:\s*\((?:\s*(?-xism
    s*\)\s*))+)*\s*\)\s*)+|\s+)*)|(?-xism:(?-xism:(?-xism:\s*\((
    ?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\
    x0D]))|(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-x
    ism:\\(?-xism:[^\x0A\x0D]))|)+)*\s*\)\s*))+)*\s*\)\s*)+|\s+)
    *<DQ>(?-xism:(?-xism:[^\\<DQ>])|(?-xism:\\(?-xism:[^\x0A\x0D
    ])))+<DQ>(?-xism:(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\
    \]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|(?-xism:\s*\((?:\s*(?-
    xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|)
    +)*\s*\)\s*))+)*\s*\)\s*)+|\s+)*))\@(?-xism:(?-xism:(?-xism:
    (?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(
    ?-xism:[^\x0A\x0D]))|(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[
    ^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|)+)*\s*\)\s*))+)*\
    s*\)\s*)+|\s+)*(?-xism:[^\x00-\x1F\x7F()<>\[\]:;@\,.<DQ>\s]+
    (?:\.[^\x00-\x1F\x7F()<>\[\]:;@\,.<DQ>\s]+)*)(?-xism:(?-xism
    [^\x0A\x0D]))|(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+
    ))|(?-xism:\\(?-xism:[^\x0A\x0D]))|)+)*\s*\)\s*))+)*\s*\)\s*
    )+|\s+)*)|(?-xism:(?-xism:(?-xism:\s*\((?:\s*(?-xism:(?-xism
    (?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A
    \x0D]))|)+)*\s*\)\s*))+)*\s*\)\s*)+|\s+)*\[(?:\s*(?-xism:(?-
    xism:[^\[\]\\])|(?-xism:\\(?-xism:[^\x0A\x0D])))+)*\s*\](?-x
    ism:(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism
    (?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0D]))|)+)*\s*\)\s*))
    +)*\s*\)\s*)+|\s+)*))))(?-xism:\s*\((?:\s*(?-xism:(?-xism:(?
    \s*(?-xism:(?-xism:(?>[^()\\]+))|(?-xism:\\(?-xism:[^\x0A\x0
    D]))|)+)*\s*\)\s*))+)*\s*\)\s*)*)"
      .Replace("<DQ>", "\"")
      .Replace("\t", "")
      .Replace(" ", "")
      .Replace("\r", "")
      .Replace("\n", "");
    #endregion

    private static Regex mailbox =
      new Regex(gibberish, RegexOptions.ExplicitCapture);

    public bool WellFormed(string address)
    {
      return mailbox.IsMatch(address);
    }
  }

  [TestFixture]
  public class Test
  {
    private SyntaxChecker checker = null;

    [SetUp]
    public void SetUp()
    {
      checker = new EmailAddressChecker();
    }

    [Test]
    public void SimpleAddress()
    {
      Assert.IsTrue(checker.WellFormed("***@example.com"));
    }

    [Test]
    public void MustHaveLocalAndDomain()
    {
      Assert.IsFalse(checker.WellFormed("justlocal"));
    }

    [Test]
    public void AmpersandInLocalPart()
    {
      Assert.IsTrue(checker.WellFormed("\"foo & ba***@example.com"));
    }

    [Test]
    public void PhraseAndAngles()
    {
      Assert.IsTrue(checker.WellFormed("Joe <j**@example.com>"));
    }

    [Test]
    public void AddressAndComment()
    {
      Assert.IsTrue(checker.WellFormed("***@example.com (Joe)"));
    }

    [Test]
    public void ContainsSingleQuoteInParenComment()
    {
      Assert.IsTrue(checker.WellFormed("ole***@example.com (Mr. O'Leary)"));
    }

    [Test]
    public void ContainsSingleQuoteInBareComment()
    {
      Assert.IsTrue(checker.WellFormed("Mr. O'Leary <ole***@example.com"));
    }

    [Test]
    public void ContainsSingleQuoteInLocalPart()
    {
      Assert.IsTrue(checker.WellFormed("o'le***@example.com"));
    }
  }
}

Issue with FileStream on network with transfers larger than 64 megabyte?
SaveFileDialog locks the file?
How to get the Appdomain Object from AppDomain ID
Why am I getting an Out Of Memory Exception
HashTable.Add Modifies HashTable Items?