List sending sources
Email may originate from mailboxes, website forms, CRM, shop platforms and newsletter systems. Identify all senders and their providers’ requirements before changing records. Missing one service may disrupt its messages. Review current operator settings rather than copying values from unrelated examples. Keep the list updated when new services are introduced.
Understand SPF and DKIM
SPF describes servers allowed to send for the domain used in the technical sender address. DKIM signs messages and allows signature verification using a DNS key. The mechanisms concern different message components. Configuration needs values supplied by the actual service providers, rather than a universal set of records copied between domains.
Introduce DMARC in stages
DMARC checks alignment between the visible sender domain and a domain authenticated by SPF or DKIM. The policy must account for legitimate sending from every system. Review reports and correct problems before enforcing stronger rules. Do not immediately reject mail while valid sources still need verification.
Check actual messages
Test email from each service and inspect authentication results in headers. Consider provider changes and new integrations. Correct records reduce impersonation and help message assessment, but do not guarantee inbox placement. Reputation, content and recipient rules also affect delivery. Repeat the checks after significant changes to your sending setup.