Useful Tools

MXtoolbox

This test will list MX records for a domain in priority order. The MX lookup is done directly against the domain's authoritative name server, so changes to MX Records should show up instantly.

http://mxtoolbox.com/

intoDNS

IntoDNS checks the health and configuration and provides DNS report and mail servers report.

And provides suggestions to fix and improve them, with references to protocols’ official documentation.

http://www.intodns.com/

Wormly

This free online tool allows you to test an SMTP mail server directly, sending a test email so you can be sure that it is functioning correctly. Perfect for setting up new mail exchangers (MX's) for your domain.

https://www.wormly.com/