• B2JContact 2.1.9
  
• Joomla 3.5.0 (but shouldn't effect this bug)
  

I have a valid email address ([email protected]) The regex that validates the email field claims this is an invalid email (it's completely valid).

Line 850 of file com_b2jcontact/helpers/fieldsbuilder.php
if(!(preg_match('/^[a-z0-9._%+-][email protected][a-z0-9.-]+\.[a-z]{2,4}$/', strtolower($post_value)) == 1)) return false;

needs an update to something like:
if(!(preg_match('/^[a-z0-9._%+-][email protected][a-z0-9.-]+\.[a-z]{2,11}$/', strtolower($post_value)) == 1)) return false;

but I'm pretty sure DNS allows up to 60ish characters, so your call how you want to handle that.