MX Lookup

MX Lookup

Look up the mail exchanger (MX) records of a domain to see which servers receive its e-mail. Enter a domain or an e-mail address — gmail.com or [email protected] — and the tool lists every MX host sorted by priority, with the record TTL.

How e-mail routing uses MX records

When someone sends a message to [email protected], the sending server queries the MX records of example.com, sorts them by preference value and connects to the lowest-numbered host on port 25. Backup MX hosts with higher numbers take over when the primary does not answer. That makes MX records the single most important DNS setting for receiving mail.

Recognising mail providers

MX hostnames reveal who handles a domain's mail:

• Google Workspace: smtp.google.com or the older aspmx.l.google.com set.
• Microsoft 365: <domain>.mail.protection.outlook.com.
• Zoho Mail: mx.zoho.com, mx2.zoho.com.
• Proton Mail: mail.protonmail.ch.
• Security gateways such as Mimecast or Proofpoint appear when mail is filtered before reaching the mailbox.

Troubleshooting checklist

If mail is bouncing, confirm that the MX records exist, that they point to hostnames (not IPs), and that those hostnames resolve — check them with Hostname to IP. Then verify the SPF, DKIM and DMARC TXT records with the DNS Lookup, and make sure the sending IP has a reverse name using IP to Hostname. After switching providers, remember that old MX records stay cached until their TTL expires.