MX Record Lookup Tool
MX Lookup is a diagnostic tool used to identify and verify the mail servers responsible for receiving email for a specific domain name. It reveals server hostnames and their relative priority.
Verify where emails for your domain are being routed. Check Mail Exchange priorities and destination servers.
Type a domain to check DNS records.
What is an MX Record?
An MX (Mail Exchanger) record is a vital component of the Domain Name System (DNS) that directs email traffic to the correct mail servers for a domain. Without valid MX records, you would be unable to receive emails at your custom domain name (e.g., hello@example.com).
When someone sends an email to your domain, the sender's mail server performs an MX lookup to identify which server is responsible for accepting messages on your behalf. These records don't just point to a server; they also include a **priority value** (preference) that allows you to set up primary and backup mail servers for high availability.
How Priority Works
MX records use a numerical priority system. The lowest number represents the highest priority (the primary mail server).
Priority 10: mx1.example.com (Primary)
Priority 20: mx2.example.com (Backup)
Priority 30: mx3.example.com (Failover)
If the primary server is offline or busy, the sending server will automatically attempt to deliver the message to the next server in the list (Priority 20, then 30).
If you have two records with the same priority, the sending server will pick one at random, effectively load balancing the incoming email traffic between them.
The Path of an Email Message
DNS Query
Sender SMTPServer queries DNS for MX records of the recipient's domain to find the authorized gateway.
Pre-flight Check
The sender sorts servers by priority and checks if they can establish a connection via port 25 (SMTP).
SMTP Handshake
If the IP is valid, the sender delivers the email. The recipient server then filters it via SPF/DKIM/DMARC.
Critical Warnings & RFC Rules
No CNAMEs in MX Target
An MX record must always point to a hostname that has an A or AAAA record. Pointing an MX record to a CNAME alias is a violation of RFC 2181 and can cause mail to be lost or delayed as many mail servers will reject the lookup.
Propagation & TTL
When switching mail providers (e.g., moving to Google Workspace or Microsoft 365), lower your TTL to 300 seconds 24 hours before the move. Use our TTL Checker to monitor cache expiry during the transition.
MX Record Frequently Asked Questions
Can I have multiple MX records?
Yes, and it is highly recommended. Most professional setups have at least two or three MX records. This provides resilience; if one data center goes offline, your emails are queued at the backup server instead of being bounced back to the sender.
What is a "Null MX" record?
A Null MX is a special record (Priority 0, target ".") used to explicitly state that a domain **does not receive email**. This is great for subdomains that only serve web content, as it prevents spammers from trying to delivery mail to them.
Why is my MX lookup showing old data?
This is almost always due to DNS Caching. Your local ISP or your computer may be remembering the old record until its TTL expires. You can use our lookup tool to see the real-time data from authoritative servers.
Is MX priority the same for all DNS?
The priority logic is a global standard defined by the IETF. However, some DNS providers might use different labels for it (like "Preference"). The rule is always: lower number = higher preference.
Beyond MX: SPF, DKIM, and DMARC
While MX records tell the world where to send mail, they don't prove that the mail you send is authentic. To ensure your outgoing emails don't end up in spam, you must configure three additional security records alongside your MX setup: