Tools
MX record lookup
Resolve every MX record for a domain, sort by priority, and resolve each MX hostname to its A records so you see the full delivery path receivers will take.
What MX records mean
- Priority — lower number = tried first. Equal priorities load-balance.
- Exchange — the hostname that accepts SMTP for this domain. Must be a name with A or AAAA records, never an IP, never a CNAME (RFC 2181 §10.3).
- No A record on the exchange — the MX points at a name that does not resolve. Mail bounces with a "host not found" SMTP error.
Send mail to any of those MXes
SNDR's outbound MTAs do exactly this lookup on every send, then try delivery in priority order with proper retry semantics. Start free.