Email & AuthenticationRFC 5321
MX Record — MX Record (Mail Exchange)
Specifies the mail servers responsible for accepting incoming email messages on behalf of the domain.
RECORD TYPE
MX
STANDARD RFC
RFC 5321
DEFAULT TTL
3600 seconds (1 hour)
CATEGORY
Email & Authentication
BIND Zone File Syntax Example
example.com. 3600 IN MX 1 aspmx.l.google.com.
example.com. 3600 IN MX 5 alt1.aspmx.l.google.com.How to Query & Check MX Records
Linux / Mac (dig)
dig +short MX example.comWindows / Generic (nslookup)
nslookup -type=MX example.comPowerShell (Resolve-DnsName)
Resolve-DnsName -Name example.com -Type MXRecommended Best Practices
Always point MX records to hostnames, NEVER directly to IP addresses. The target hostnames must themselves resolve to A/AAAA records.
Primary Use Cases:
- •Connecting domains to Google Workspace / Gmail for business
- •Configuring Microsoft Exchange / Office 365 mail routing
- •Setting up backup fallback mail servers with higher priority numbers
Common Configuration Mistake
Forgetting trailing dots in BIND zone files, causing hostnames to become `aspmx.l.google.com.example.com`.
Always verify records using authoritative queries (`dig @1.1.1.1 $MX example.com`) to bypass local ISP caching when debugging propagation delays.
Frequently Asked Questions
DNS MX Record Questions & Answers
Common questions regarding DNS propagation, TTL settings, and zone file syntax.
MX (Mail Exchange) records route incoming emails to mail providers like Google Workspace, Microsoft 365, Fastmail, or ProtonMail. Each MX record includes a priority preference number; sending MTAs attempt the lowest priority number first.