Email

Validating email addresses is much more difficult than one would think until they have attempted to do so. Over the last 10 years or so anytime I have the need I consult this page first.

Very nice tool to check your email deliverability. You send one email from your email provider and it does a full check to see if your domain, DNS and email provider are configured correctly to be trusted by receiving email servers across the internet.

Maintenance check for your email domain DNS settings to ensure deliverability. This one checks your email domain appears publicly to be configured correctly. It's a good reference to check routinely to ensure DNS changes don't break your email setup. When setting up or changing email configurations/providers the Mail Tester utility is a more complete test with an actual email transaction.