When sending email it’s a best practice that your sending ips reverse and forward resolutions match.

When looking up IPv4 addresses you use a special domain called in-addr.arpa so if you want to know the ptr of 8.8.4.4 just run this

See the name = in the answer, that’s the PTR not to see if we have a confirmed forward and are good to go we need to see if the domains A-record match the IP we looked up. Run this

See the Address part in the answer it matches the ip we checked PTR on. That means that they are matching.

ktnxbye!

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