Mail servers for a domain
DNS & Records
DNS Lookup Every DNS record for any domain A Record Lookup IPv4 addresses for a domain AAAA Record Lookup IPv6 addresses for a domain MX Lookup Mail servers for a domain NS Lookup Authoritative name servers TXT Lookup TXT records, SPF, verification CNAME Lookup Canonical name (alias) records SOA Lookup Start of Authority record SRV Lookup Service location records CAA Lookup Which CAs may issue certificates Reverse DNS (PTR) IP address to hostname DNSSEC Check Is the domain signed and validated? DNS Health Check A full delegation & DNS report cardEmail Deliverability
SPF Check Validate your Sender Policy Framework record DMARC Check Inspect and grade your DMARC policy DKIM Check Find and validate your DKIM public key Blacklist Check Check an IP against email blocklists (DNSBLs) SMTP Test Connect to a mail server and check STARTTLS MTA-STS Check Enforced TLS policy for inbound mail BIMI Check Brand logo record for email TLS-RPT Check SMTP TLS reporting policyNetwork & Web
SSL Certificate Check Inspect a site's TLS certificate and expiry HTTP Header Check Inspect response headers, redirects and security Ping (TCP) Reachability and latency over TCP Port Check Which common ports are openDomain
WHOIS Lookup Registration data for domains, IPs and ASNsAn MX (Mail Exchanger) record tells sending servers which hosts accept email for a domain and in what priority order. When someone emails you, their server queries your MX records to find where to deliver. A missing or misconfigured MX record means inbound mail cannot be delivered and messages bounce or vanish.
Each MX record pairs a mail host with a priority number. Lower numbers win: a sending server tries the lowest-priority host first and falls back to higher numbers only if it cannot connect. To balance load across equally capable servers, give them the same priority and traffic spreads between them. A typical Google Workspace setup, for example, points to smtp.google.com at priority 1. The MX value must be a hostname with its own A or AAAA record, never an IP address or a CNAME, or delivery breaks.
IPeek lists every MX host for the domain with its priority, sorted lowest-first so the preferred server sits at the top. Confirm the hosts match your email provider: Google Workspace, Microsoft 365, your own server or a filtering gateway. Watch for duplicates, typos in hostnames, or trailing dots that signal a misconfigured zone. If the list is empty, the domain has no MX records and cannot receive mail. Cross-check the listed hosts resolve to valid IP addresses before trusting them.
The most frequent failure is no MX record at all, which forces senders to fall back to the domain's A record or bounce. Pointing an MX at a CNAME violates the spec and many servers reject it, so always target a hostname with a direct A/AAAA record. After switching email providers, stale MX records keep routing mail to the old host until DNS propagates and caches expire. Misordered priorities can send mail to a backup before the primary. Verify changes with a fresh lookup and allow for TTL-based caching.
Without an MX record, sending servers fall back to the domain's A or AAAA record and attempt delivery there. If that host does not run a mail server, the message bounces. Domains that handle email should always publish at least one MX record so inbound mail reaches the correct server reliably.
The priority sets the order in which sending servers try your mail hosts, and lower numbers are preferred. A server attempts the lowest-priority host first and moves to higher numbers only if it cannot connect. Equal priorities let servers share load. The actual values are arbitrary; only their relative order matters.
No. An MX record must point to a hostname that has its own A or AAAA record. Pointing it at an IP address is invalid, and pointing it at a CNAME violates RFC rules and is rejected by many mail servers. Always target a real mail-host name that resolves directly.
MX changes propagate according to the record's TTL, which controls how long resolvers cache the old values. With a low TTL, changes can apply within minutes; with a higher TTL, sending servers may keep using stale records for hours. Lower the TTL before a planned migration to speed the cutover.
Yes. Domains commonly publish several MX records for redundancy and load balancing. Different priorities create a primary-and-backup arrangement, while identical priorities spread mail across equally capable servers. A sending server walks the list in priority order until it finds a host that accepts the connection.