Note: Run in production IFF you want a DOS opportunity on your hands :) This is a perfect example of why not to use regular expressions to validate email addre

Note: Run in production IFF you want a DOS opportunity on your hands :) This is a perfect example of why not to use regular expressions to validate email addresses. It likely (1) still misses some edge cases, (2) is nearly impossible to verify, and (3) is exponentially expensive (see 2).