we use Brevo (formerly SendinBlue) in our network postoffice for relaying emails. 90%+ delivery rate.
https://www.brevo.com/
pretty simple setup. point mx/DNS to a host that will allow external smtp routing (A2hosting etc), get a dedicated IP at brevo, and use their API to send emails.
i'm surprised at the YNOT issues tho. did you message Rochard?
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