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The Complete Guide to Email Authentication: SPF, DKIM, DMARC, and BIMI

SPF, DKIM, DMARC, and BIMI help prove that your email is legitimately from you. Here is the plain-language version of what each one does.

Email authentication tells receiving systems that your mail is actually coming from the domain it claims to come from.

That matters because even a well-targeted campaign looks less trustworthy when authentication is weak.

SPF

SPF defines which senders are allowed to send on behalf of your domain.

DKIM

DKIM adds a cryptographic signature so receiving systems can verify the message was not altered.

DMARC

DMARC tells receiving systems how to handle messages that fail authentication and helps you monitor what is happening.

BIMI

BIMI is the branding-oriented layer that can display your logo in supported inbox experiences, but it depends on stronger authentication foundations.

Why this matters alongside list cleaning

Authentication and list hygiene solve different problems:

  • authentication helps prove the sender is legitimate
  • list cleaning helps prove the recipients are worth sending to

You want both.

Clean the list while you tighten delivery fundamentals on MailCull →

Keep reading

Read next Email List Cleaning for E-Commerce: Protect Your Campaigns and Save on ESP Costs For ecommerce teams, list hygiene is not just a technical task. It directly affects campaign reach, cost, and revenue confidence. Also read Why Purchased Email Lists Are a Bad Idea A practical look at why bought lists damage deliverability and why organic growth beats shortcuts.