Update README.md

README.md

@@ -67,7 +67,8 @@ $validator->isValid("[email protected]", new RFCValidation()); //true
 2. [NoRFCWarningsValidation](/src/Validation/NoRFCWarningsValidation.php): RFC-like validation that will fail when warnings* are found.
 3. [DNSCheckValidation](/src/Validation/DNSCheckValidation.php): Will check if there are DNS records that signal that the server accepts emails. This does not entails that the email exists.
 5. [MultipleValidationWithAnd](/src/Validation/MultipleValidationWithAnd.php): It is a validation that operates over other validations performing a logical and (&&) over the result of each validation.
-6. [Your own validation](#how-to-extend): You can extend the library behaviour by implementing your own validations.
+6. [MessageIDValidation](/src/Validation/MessageIDValidation.php): Follows [RFC2822 for message-id](https://tools.ietf.org/html/rfc2822#section-3.6.4) to validate that field, that has some differences in the domain part.
+7. [Your own validation](#how-to-extend): You can extend the library behaviour by implementing your own validations.
 
 *warnings: Warnings are deviations from the RFC that in a broader interpretation are acceptded.