We often recommend checking that boxes are set up correctly using live validation tools that have been developed by other people. What tools do you use? Here are some:
I’ve updated this post to include all of the tools mentioned in the comments below as of July 2020.
Peculiar as with the tools I use, DNSSEC checks come out ok, but with your tools it tells me everything is insecure and that my domains aren’t in a zone!?
I once was rejected by AT&T for being on a blacklist that the more popular blacklist providers did not have me listed on.
I discovered it was a blacklist that blocks IP addresses that have never before been used for sending mail, though now I’ve forgotten which one it was (it was very easy to get off of).
Maybe someone can making a nice list with some descriptions of each service and prioritize the ones that are most helpful. We can add it to our setup guide / website.
I find GWhois.org useful for certain DNS and WHOIS checks. The site does not cache any records, so every lookup is resolved from root servers. It was created before RFC 8482 was published and I don’t think the developer is going to rewrite the code (which is on GitHub) to work around this limitation.
Most of the popular DNS providers do not answer to ANY requests, but MiaB does, and this is where it is a very useful tool to quickly view most of the records of concern when troubleshooting, and since everything is resolved there is no need to wait for records to “propagate”.
When I don’t have access to command line or want a quick second opinion from a different IP address, I use DNSQueries because it has almost every lookup I’ve ever needed built into a PHP interface.