MX record
An MX record is the DNS record naming the servers that accept mail for a domain, each with a priority number, where lower numbers are tried first. Without one a domain can send mail but cannot receive it. Changing the record at the root of a domain moves every address at once, which makes it a decision rather than a setting.
At a glance
- Category
- DNS
- Names
- The hosts that accept mail for a domain
- Priority
- Lower is tried first; equal values share the load
- Points at
- A hostname, never an address literal
- Affects
- Receiving only — sending needs no MX record
- Specified in
- RFC 5321
How it works
A sending server takes the domain to the right of the at sign, looks up its MX records and gets a list of hostnames with priority numbers. It tries the lowest number first and falls back to the next if that host refuses or does not answer. Hosts sharing a priority are tried in a rotating order, which is the usual way to spread load. Each hostname is then resolved to an address and connected to; a record pointing directly at an address is invalid.
Why it matters
The MX record is the switch that decides where a domain's mail lands, and it operates on the whole domain at once. That is why pointing the root of a company domain at a new service to try inbound parsing is a genuinely dangerous experiment: every mailbox moves in the same instant. It is also why the absence of a record is such a common confusion — a domain with no MX can still send perfectly well, so nothing looks wrong until somebody replies. The record is read by the sender, never by you, which is why a change is invisible from the inside until mail stops arriving.
Example
A team wants to receive support replies through their application. Rather than touching example.com, they publish an MX record for support.example.com pointing at the receiving service with priority 10. Mail to anything at support.example.com now arrives at their endpoint, while every existing mailbox at example.com is untouched. Later they add a second host at priority 20 as a fallback.
Common mistakes
- 01Pointing an MX record at an IP address rather than a hostname, which is invalid and rejected by careful senders.
- 02Changing the record at the root of the domain to try something out, which redirects every mailbox in the organisation at once.
- 03Leaving an old provider's record in place at a higher priority, so some mail quietly continues to arrive somewhere nobody reads.
- 04Publishing a single MX record with no fallback host, so a few minutes of downtime pushes every sender into its retry queue.
In Rasket
Receiving takes one MX record, published at the inbound label by default, or at the root of the domain when every address there should reach us. Receiving
Related terms
Frequently asked questions
Do I need an MX record to send email?
No. Sending is governed by authentication records and the sending service. An MX record only tells other servers where to deliver mail addressed to your domain.
What do the priority numbers mean?
They are a preference order, not a weight. The lowest number is tried first, and equal numbers are used in rotation to spread the load between hosts.
Can a domain have MX records at more than one provider?
Technically yes, but splitting live mail between providers by priority is a common way to lose messages. Use a subdomain for the second destination instead.
Sources
Last updated 16 September 2026.
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