MX Records and Email Deliverability: A Complete Guide
Mail Exchanger (MX) DNS records tell internet mail servers which host is responsible for accepting email messages on behalf of a recipient's domain.
How MX Records Work
MX records contain two key fields:
- Mail Exchanger Hostname: The fully qualified domain name (FQDN) of the mail server (e.g.
aspmx.l.google.com). - Priority / Preference: An integer value indicating server preference. Lower numbers mean higher priority.
When a sender attempts to deliver email to user@example.com:
- The sending server queries DNS for MX records of
example.com. - It attempts connection to the server with the lowest priority value (e.g., Priority 5).
- If that server is unreachable, it falls back to secondary servers (e.g., Priority 10 or 20).
Common Email Providers & MX Configurations
- Google Workspace:
aspmx.l.google.com(Priority 1),alt1.aspmx.l.google.com(Priority 5). - Microsoft 365:
domain-com.mail.protection.outlook.com(Priority 0). - ProtonMail:
mail.protonmail.ch(Priority 10),mailsec.protonmail.ch(Priority 20).
Free MX Lookup Tool
Test your domain's mail server setup with our free MX Record Lookup tool, featuring automatic provider detection and priority sorting.
title: "MX Records and Email Deliverability" description: "Understand MX records, priorities, and how DNS mail routing affects email delivery." date: "2026-08-12" author: "DevTools" tags: ["dns", "mx", "email", "deliverability"] relatedTools:
- name: "MX Lookup" href: "/mx-lookup"