I added a domain to my MIAB and it passes all of the email tests that you can do online. However, I just sent a demo email from the one in MIAB to an email I use guarded by Barracuda but it says:
Message was quarantined due to Sender Policy Framework (SPF) (Fail).
If you are referring to an online tool to test something like an SPF record, those tools usually can only test that the syntax is correct. Only you can know if the configuration is correct, because there are too many factors for the tool to take into account.
Usually the tools that require you to send to them an email will be the most accurate for the message sent, because they are verifying if the message is in compliance with DNS records.
Maybe I wasn’t super clear - I have done several of those tests where you directly send them an email, and everything, besides not having an unsubscribe footer is correct and looks good - so I’m not sure what else Barracuda is wanting
What is different when using the iPhone/Exchange client? I know some of those tools use their own SMTP server.
Does Barracuda add anything to the headers that might be a clue as to why they think it is spam? And is there anything in the message transaction in /var/log/mail.log?