How to Set Up DKIM on GoDaddy
Some DNS providers may create DNS records with a duplicate the domain name, causing "mailpoet1._domainkey.example.com" record to be incorrectly created as "mailpoet1._domainkey.example.com.example.com". This is the case of GoDaddy, for example.
If that's the case, you'll see the records showing as "Invalid" on your MailPoet 3 account.
To confirm this is what's happening, you can use the online tool https://www.mail-tester.com/spf-dkim-check
Duplicate the domain like this and check if you find a record for it:
In this case, please remove the domain name from the record's name, leaving it as " mailpoet1._domainkey", "mailpoet2._domainkey" and "_mailpoet".