How do you get an email address within a string

I am pulling many ema开发者_如何学Pythonils from an Exchange 2003 server and from those emails, trying to determine which are bounce-backs (invalid) so I can remove them from our contacts.

What would be the most efficient method of searching the email bodies to find email addresses on the bounce backs?

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You might want to look at this page, which has several variants of regexes for matching email addresses and explains the trade-offs for selecting each. You should definitely read it before picking one here.

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Just use a regex.

\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b

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This is the regex that we use in a lot of our applications for email validation;

public static bool CheckEmail(string email)
    {
        //validate Email
        Regex regex = new Regex(@"^([a-zA-Z0-9_\-\.\']+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})$", RegexOptions.IgnoreCase);
        Match match = regex.Match(email);
        return match.Success;
    }

The actual process for correctly identifying a bounced email, rather than an auto-reply or genuine message is a little more complicated, but this will at least give you the email address.

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I pulled a few of the answers here into something like this. It actually returns each email address from the string (sometimes there are multiples from the mail host and target address). I can then match each of the email addresses up against the outbound addresses we sent, to verify. I used the article from @plinth to get a better understanding of the regular expression and modified the code from @Chris Bint

However, I'm still wondering if this is the fastest way to monitor 10,000+ emails? Are there any more efficient methods (while still using c#)? The live code won't recreate the Regex object every time within the loop.

public static MatchCollection CheckEmail(string email)
{
  Regex regex = new Regex(@"\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b", RegexOptions.IgnoreCase);          
  MatchCollection matches = regex.Matches(email);

  return matches;
}