Null MX validation

[jace]

RFC 7505 specifies "null MX" for when a domain explicitly does not support email. This is testable with the example.* domains:

example.org mail is handled by 0 .

However, pyIsEmail when using check_dns=True does not test for RFC 7505 and accepts null MX records as valid.

>>> is_email('[email protected]', check_dns=True, diagnose=True)
<ValidDiagnosis: VALID>

[michaelherold]

This looks reasonable. I'd be happy to accept a PR.

[IPENprj]

Hi there, Is this why Domains with MX that has no A Record, validated?

[bmcculley]

Opened PR #22 which checks the returned MX record(s) preference.