I had this problem for years. I would get the block lifted and it would return in short order. I surmise itβs because my mail server runs on a VPS and other users on my subnet are not well behaved (actually I know this for a fact).
I solved the problem by paying for a next hop SMTPS server as an upstream smarthost for non-local mails. That means my mails come from a subnet that fronts TONS of other servers/domains. That makes it a bigger headache for MS to block.
Sad but there you go. I do not use the external service for inbound. Inbound mails come direct to my server per the MX.
I solved the problem by paying for a next hop SMTPS server as an upstream smarthost for non-local mails. That means my mails come from a subnet that fronts TONS of other servers/domains. That makes it a bigger headache for MS to block.
Sad but there you go. I do not use the external service for inbound. Inbound mails come direct to my server per the MX.