Mastering Email Deliverability: DNS, MX, SPF, DKIM, and DMARC Explained

The Science of the Inbox

Setting up an email account is only half the battle. Ensuring your emails actually arrive in your client's inbox requires a technical foundation of DNS records.

1. MX Records (Mail Exchange)

These records tell the world which server is responsible for receiving your email. Without correct MX records, you simply won't receive any mail.

2. SPF (Sender Policy Framework)

An SPF record is a text record in your DNS that lists all the IP addresses authorized to send email on behalf of your domain. It prevents 'spoofing'.

3. DKIM (DomainKeys Identified Mail)

DKIM adds a digital signature to your emails. This signature is verified by the recipient's server to ensure the email wasn't tampered with during transit.

4. DMARC (Domain-based Message Authentication, Reporting, and Conformance)

DMARC uses SPF and DKIM to tell receiving servers what to do if an email fails authentication. It can be set to 'none' (monitor), 'quarantine' (spam folder), or 'reject' (block entirely).

Pro Tip: Always use a tool like MXToolbox to verify your records after any changes. A single typo in your SPF record can block your entire company's outgoing mail.

Common DNS Record Examples:

• SPF: v=spf1 include:_spf.google.com ~all
• DMARC: v=DMARC1; p=quarantine; rua=mailto:admin@yourdomain.com