Resolve Recipient Server Blocks

A specific recipient's mail server has a policy that blocks your message, often deliberately.

Why this happens

Blocking senders not on an internal allow list. Rejecting borderline reputation scores. Content-based filters. Requiring pre-approval.

Different from an invalid address or blocklist listing — a deliberate policy decision, sometimes fixed on their end.

How to resolve it

1. Confirm SPF/DKIM/DMARC all pass.
2. Check general sender reputation.
3. Clean up content, check text-to-image ratio.
4. Reach out to the recipient organization directly for important contacts, asking to be allow-listed.

What to expect

Authentication fixes: a day or two. Reputation issues: a few weeks. Allow-list requests: depends on the organization.