Thanks for your reply and support.
Yes to: DNS correct with an MX record in place? Verify with dig.
Yes to: CSF firewall set with SMTP ports (25, 465, 587) open?
Started with Calm and SpamAssassin to:
Are you starting without Clam and Amavis and SpamAssassin in the mail transport chain for simplicity?
re fix the spf record ...
re build the mail server
with opendkim on
-> I started with opendkim on and rebuild the mail server once already.
and try to sent email to mail-tester.com .. not to gmail
if you test sent email to gmail... you need "all green"
-> As I mentioned, the emails remain stuck in the queue, so it does not go anywhere byond the queue it would seem :-)
Issues not resolved yet.