Email Deliverability Guide

Email Authentication: SPF, DKIM and DMARC

Email authentication helps receiving providers check whether a message is connected to the domain it claims to represent. SPF, DKIM and DMARC work together, but each one solves a different part of the problem.

SPF: who is allowed to send

SPF is a DNS TXT record that lists the servers or services authorized to send mail for a domain.

DKIM: a cryptographic signature

DKIM adds a digital signature to outgoing email that receivers can verify using a public key in DNS.

DMARC: alignment and policy

DMARC checks whether authenticated identities align with the domain visible to the recipient and can publish a handling policy.

Set up authentication in the right order

1. List every legitimate sending platform.
2. Configure SPF.
3. Enable DKIM and publish provider-supplied records.
4. Confirm SPF and DKIM pass.
5. Add DMARC and monitor reports.
6. Repeat checks after provider or DNS changes.

InboxCan shows placement in the Gmail accounts connected to this site. It is a testing signal, not a guarantee of placement for every recipient.