Hello all,
So the mystery has been solved !!
For future reference, I thought I had taken all the steps needed to move my email domain to a new server.
I raised the question here because is a new software for me, and this looked very strange and weird, but in fact, was a security measure implemented, and in fact, it does work as needed.
The issue is related to the MTA-STS policy implemented on my MIAB setup, which ‘enforces’ the use of the email server declared on the policy. This will take 7 days to disappear so, but this is a non-PROD domain, that mainly receives status from other servers.
The question is ‘Why is Gmail the only provider respecting this policy?’
For the future …
Best regards, and many thanks to all.
Jorge Gomes