Key controls
- Require authenticated SMTP.
- Enforce strong mailbox passwords.
- Monitor mail queue.
- Limit outbound mail for new or suspicious accounts.
- Configure SPF, DKIM, DMARC, hostname, and reverse DNS.
- Suspend or clean compromised senders quickly.
If blacklisted
Find and stop the source first. Then review logs, clean compromised accounts, reset passwords, and request delisting only after the problem is resolved.
Server owner responsibility
Owning a server includes updates, firewall, backups, monitoring, licenses, abuse response, mail reputation, DNS, and customer communication. Keep a written checklist so routine tasks are not handled from memory.
Quick support handoff
If this article does not solve the issue, open a support ticket with the domain, service name, exact error, time the problem started, and what changed recently.
