MX Records and Email Deliverability: Correct Configuration

The MX (Mail Exchange) record is a DNS record that determines which server email addressed to a domain is delivered to. A misconfigured MX record means all incoming email is lost or sent to the wrong place. Correct configuration, on the other hand, ensures uninterrupted and reliable delivery.

How Does an MX Record Work?

When you send someone an email, the receiving server follows these steps:

1. It queries the recipient domain’s DNS: “Where is this domain’s MX record?”
2. DNS returns the MX server name and priority value
3. The sender connects to the MX server with the lowest priority number
4. If that server is busy or unreachable, it moves on to the next MX

Priority Values

In an MX record, the lower the priority value, the higher the priority of that server.

yourdomain.com  MX  10  mail1.ulakmail.com   ← Primary server
yourdomain.com  MX  20  mail2.ulakmail.com   ← Backup server
yourdomain.com  MX  30  mail3.ulakmail.com   ← 3rd backup

If multiple records share the same priority, the sender randomly picks one (load balancing).

Why Is a Backup MX Server Important?

In a domain with only one MX record, if the primary server is offline, incoming emails can be lost or bounce back. A backup MX server:

• Temporarily stores email while the primary is in maintenance or outage
• Forwards the queued mail once the primary is back online
• Provides delivery assurance

Correct MX Configuration: Step by Step

1. Open the DNS panel — Your domain registrar’s or hosting provider’s DNS management screen

2. Add the MX records:

3. Verify the A record — The hostname in the MX record must resolve to an IP via an A record

4. Delete old MX records — Remove the old record after the change; conflicts cause delivery problems

5. Lower the TTL temporarily — Drop the TTL to 300 seconds before the change, then raise it back to 3600 afterwards

Common MX Mistakes

The Relationship Between MX and SPF

You also need to declare your MX server in your SPF record. Otherwise, emails sent through that server will fail SPF validation.

v=spf1 mx include:_spf.ulakmail.com ~all

The mx parameter automatically includes all servers listed in the MX records into SPF. For details, see our SPF, DKIM, and DMARC guide.

Check Your MX Record

With our MX lookup tool, you can instantly check your domain’s MX records, priority values, and server reachability.

Frequently Asked Questions

Will my emails be lost when I change the MX record? The old system continues to work until the TTL expires. If you lower the TTL ahead of time and execute the change carefully, a zero-downtime migration is possible.

How many MX records should I have? A minimum of 2 (primary + backup) is recommended. More than 3 is generally unnecessary.

My MX record exists but I’m not receiving email — what should I do? First, confirm that the record has propagated using MX lookup. Then run a blacklist check. DNS propagation can take 24–48 hours.

Can MX and CNAME be used together? No. According to RFC standards, an MX record must point directly to an A record, not via a CNAME.

How do I update the MX record when I switch email providers? Your new provider gives you the new MX values. Lower the TTL, delete the old MX record, and add the new one. Ulakmail manages the migration free of charge — average duration 2–4 hours, no downtime.

MX lookup → • NS lookup → • SPF/DKIM/DMARC guide → • Email security →