Check who handles email for any domain.
Look up MX records for any domain — mail server hostnames, priorities, and infrastructure, in a single API call.
Trusted by teams at
All MX records, sorted by priority.
MX Lookup queries DNS for every mail exchange record on a domain and returns them sorted by priority ascending — lowest number first, per RFC 5321. Each result includes the mail server hostname and its numeric priority value.
{
"domain": "gmail.com",
"records": [
{ "host": "gmail-smtp-in.l.google.com.", "priority": 5 },
{ "host": "alt1.gmail-smtp-in.l.google.com.", "priority": 10 },
{ "host": "alt2.gmail-smtp-in.l.google.com.", "priority": 20 }
]
}
One GET request. Pass the domain in the URL.
No request body. No complex parsing. Pass the domain in the path, your API key in the header, and get back a sorted JSON array of MX records ready to use in your pipeline.
GET /v1/networking/mx/gmail.com
Host: requiems.xyz
requiems-api-key: YOUR_API_KEY
Built for email validation and deliverability.
MX Lookup fits anywhere email deliverability and DNS verification matter.
Verify email deliverability before sending
Check if a domain is configured to receive email before adding it to a mailing list — catch invalid domains early and reduce bounce rates.
Go beyond syntax in email validation
Syntax validation only checks format. MX Lookup confirms the domain can actually receive email — catching disposable or broken domains that syntax checkers miss.
Discover mail server infrastructure
Identify which mail providers a domain uses — useful for competitive research, due diligence, and understanding email routing before integration.
Diagnose email routing issues
Quickly check MX records when email delivery fails. Missing or misconfigured MX records are a common cause of delivery failures.
Block invalid domains at onboarding
Reject email addresses at signup if the domain has no MX records — prevents fake accounts with non-receivable email addresses.
Enrich bulk email lists
Run MX lookups on existing subscriber lists to identify domains that no longer receive email before a campaign send.
Use together with complementary APIs.
MX Lookup works even better when paired with other Requiems APIs.
Combine MX record checks with full syntax, disposable domain, and typo-correction validation for a complete email pipeline.
Check MX records alongside A, NS, and CNAME records plus domain availability in a single workflow.
Flag disposable email domains at signup while verifying the domain's MX records are real and active.
Frequently Asked Questions
Still have questions? Contact support
Automate this with Requiems.
One API key. MX Lookup, plus 50+ other APIs across DNS, email validation, networking, and more.