Custom domain email: MX, SPF, DKIM, and DMARC without the guesswork
Understand each DNS record’s job, prepare provider-specific values, and test routing, signatures, and domain alignment systematically.
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Pop MailBox Lab / Topic
Email authentication.
Email authentication helps receiving systems evaluate whether a message’s sending identities are supported by the domain’s configuration. SPF, DKIM, and DMARC contribute different checks, so one successful result does not explain the entire arrangement. Understanding their roles is especially useful when staff mail and several external business tools send under related addresses.
The email DNS and authentication guide distinguishes envelope identity, cryptographic signatures, and alignment with the visible From domain. The custom domain overview provides the broader setup context. Use these articles to ask precise questions of your providers and interpret the results of controlled test messages.
Maintain a list of legitimate senders and the owner of each service. Follow account-specific publication instructions, then verify that messages actually use the intended configuration. Investigate failures across real sending paths before strengthening domain policy. Authentication supports domain identity checks, while delivery and message safety still depend on additional factors that require their own attention.
Where to begin
Start by listing every service that sends from your domain. For one fresh message from each, inspect the visible From address and the recipient’s authentication results. Determine which identity SPF checks, which domain DKIM signs for, and whether either passing result aligns as intended for DMARC.
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