Mail Exchanger (MX) records tell the internet which servers accept email for your domain. They are essential for receiving mail—and their configuration signals whether a domain is set up like a real mailbox provider or a throwaway service.
How MX records work
MX is published as DNS records on your apex domain:
example.com MX 10 mail.example.com
example.com MX 20 mailbackup.example.comThe number is priority (lower = preferred). Servers try the lowest priority first; higher values are fallbacks.
What healthy MX looks like
Legitimate business domains typically point MX to:
- Google (
aspmx.l.google.com, etc.) - Microsoft (
*.mail.protection.outlook.com) - Their ESP or hosting provider’s mail cluster
You should see at least one MX host that resolves to an IP address.
Red flags in MX configuration
No MX records
A domain with no MX cannot receive email. Some disposable domains use clever setups, but missing MX on a “business” domain is suspicious.
MX pointing to disposable infrastructure
Temp-mail services often use dedicated MX hosts (e.g. mx.dropmail.me or provider-specific hosts). Our checker flags known disposable MX patterns during email intelligence scans.
Stale or typo MX after migration
Switching from one ESP to another without removing old MX records can cause split delivery or authentication confusion.
MX and cold email (sending)
Outbound cold email usually sends from your domain via an SMTP relay—it does not require your domain’s MX to match the sender. But receivers still look at:
- Whether your domain resolves and has DNS maturity
- Whether your sending IP is on blocklists (checked via the MX host’s IP in full audits)
Run the domain checker to list MX hosts, resolve mail server IPs, and scan major DNSBLs in one report.
Quick MX audit checklist
- At least one MX record exists
- Priorities are intentional (not random duplicates)
- MX hostnames resolve (A/AAAA records)
- Matches your actual mailbox provider after migrations
- Not pointing to known temp-mail infrastructure
MX is one line item in a full audit—pair it with SPF, DKIM, and DMARC for complete infrastructure visibility.