What Is MX Record?
An MX (Mail Exchange) record is a DNS record that tells the internet which mail servers are responsible for receiving email for a domain. Each MX record points to a hostname and carries a priority value; senders try the lowest-numbered (highest-priority) server first when delivering mail.
When someone sends an email to you@yourdomain.com, the sending server looks up the MX records for yourdomain.com in DNS to find out where to deliver the message. Without a valid MX record, inbound mail to your domain has nowhere to go and bounces — MX records are what make a domain able to receive email at all.
MX records are prioritized. The number in front of each host (0, 10, 20, and so on) is the preference value: lower numbers are tried first. Multiple MX records let you list backup servers, so if the primary is unreachable the sender falls back to the next-lowest priority. Equal priorities distribute load between servers.
MX records affect deliverability indirectly. Providers and anti-spam systems expect a receiving domain to have well-configured MX records, and mismatches or missing records can make a domain look misconfigured. For sending, what matters more is SPF, DKIM, and DMARC — but MX must be correct for replies and bounce handling to work.
How MX records route mail
MX records live in your domain’s DNS zone, alongside your A, TXT, and CNAME records. Each MX record has two parts: a priority (an integer) and the hostname of a mail server that accepts mail for the domain. That hostname must itself resolve to an A or AAAA record — an MX record may never point directly to an IP address, and per the standards it should not point to a CNAME.
Delivery works by preference order. A sending server collects all MX records for the recipient domain, sorts them by priority ascending, and attempts the lowest number first. If that host is unreachable or temporarily rejects the message, it moves to the next priority. This is why a domain often lists a primary at priority 1 or 10 and one or more backups at higher numbers.
When two or more MX records share the same priority, senders pick between them at random, spreading inbound load across the servers. Large providers like Google Workspace and Microsoft 365 publish several equal- or tiered-priority MX hosts for exactly this redundancy.
MX records and deliverability
MX records govern inbound mail, not outbound — the servers that send your cold email are authorized by SPF, signed by DKIM, and governed by DMARC, not by MX. But MX still matters for outreach: replies, bounce notifications (which arrive as inbound mail), and out-of-office responses all depend on your domain having working MX records so those messages can reach you.
A missing or broken MX record is a red flag. Some receiving systems treat mail from a domain that cannot itself receive mail as more suspicious, and you simply will not see replies or bounces. When you set up a fresh sending domain for outreach, configure its MX records to your mailbox provider before you start warming it up.
Example records
yourdomain.com. IN MX 1 smtp.google.com.
Modern Google Workspace uses a single MX host at priority 1. Older setups listed five hosts (ASPMX.L.GOOGLE.COM at priority 1, plus ALT1–ALT4 at 5 and 10). The trailing dot marks a fully qualified hostname.
yourdomain.com. IN MX 0 yourdomain-com.mail.protection.outlook.com.
Microsoft 365 publishes a single MX record at priority 0, pointing to your tenant’s protection.outlook.com host. The exact hostname is generated from your domain in the Microsoft 365 admin center.
Reading an MX record
| Field | Example value | What it means |
|---|---|---|
| Name / host | yourdomain.com | The domain the MX record applies to |
| Type | MX | Identifies this as a mail-exchange record |
| Priority | 10 | Preference — lower is tried first; equal values share load |
| Value / target | aspmx.l.google.com | Hostname of the receiving server (must resolve to an A/AAAA record) |
Frequently asked questions
What is an MX record?
An MX (Mail Exchange) record is a DNS record that specifies which mail servers are responsible for receiving email for a domain. It pairs a server hostname with a priority value, and sending servers use it to find where to deliver messages addressed to that domain. Without an MX record, a domain cannot receive email.
What does the priority number in an MX record mean?
The priority (or preference) is an integer that sets the order in which sending servers try your mail hosts. Lower numbers are tried first, so a host at priority 10 is preferred over one at 20. Backup servers get higher numbers, and records sharing the same priority split inbound mail between them.
Can an MX record point to an IP address?
No. An MX record must point to a hostname, not an IP address, and that hostname needs its own A or AAAA record to resolve to an IP. The standards also say an MX target should not be a CNAME. If you only have an IP, create an A record first and point the MX record at that hostname.
Do MX records affect email deliverability?
Indirectly. MX records control inbound mail — replies, bounces, and out-of-office messages — while outbound deliverability depends on SPF, DKIM, and DMARC. But a domain with missing or misconfigured MX records looks broken to some receivers, and you will not see replies or bounce notifications, so correct MX setup still matters for outreach.
MailPilot’s DNS health checker verifies your MX records alongside SPF, DKIM, and DMARC, so you can confirm your sending domain is set up to receive replies and bounces before you start warming it up.
Check your domain’s DNS records →