[{"data":1,"prerenderedAt":42},["ShallowReactive",2],{"$f2284mb9i01873":3},{"title":4,"seoTitle":5,"description":6,"route":7,"kind":8,"toolKey":9,"intro":10,"indexable":11,"sections":12,"related":38},"MX Lookup","MX Lookup | nslookup.online","Check MX records, mail-server priorities and Null MX declarations. Inspect supplemental A and AAAA records without claiming SMTP delivery validation.","\u002Fmx-lookup\u002F","tool","mx","Inspect mail-routing records and their priorities.",true,[13,20,26,32],{"id":14,"title":15,"paragraphs":16,"code":19},"read-answer","Read a domain’s mail routing",[17,18],"Enter the domain after the @ sign, not a full email address. An MX record names a mail exchange and its preference number. The tool sorts MX answers by numeric preference so lower values appear first.","Two targets with the same preference are peers. Their order in a resolver response does not establish a unique primary server. This tool does not connect to port 25, test a mailbox, or deliver a message.","example.com.  3600  IN  MX  10 mail.example.com.\n\nDOCUMENTATION EXAMPLE — not a live DNS response",{"id":21,"title":22,"paragraphs":23},"null-mx","What Null MX means",[24,25],"An MX record with preference 0 and target a single dot explicitly says the domain does not accept email. This is a Null MX declaration, not a mail server called dot. No address lookup is attempted for that target.","No MX record is different from Null MX: SMTP standards may use address records as an implicit fallback in some circumstances. An absent MX alone is not a universal delivery-failure diagnosis.",{"id":27,"title":28,"paragraphs":29},"addresses","Supplemental addresses and limitations",[30,31],"A and AAAA lookups can show addresses attached to returned exchange names. These are DNS observations only. They do not check whether a mail server is reachable, whether its TLS configuration is correct, or whether it accepts the intended recipient.","Address enrichment is limited to eight distinct targets to keep a browser operation bounded. Any failed supplemental query is displayed separately rather than hiding successful MX records.",{"id":33,"title":34,"paragraphs":35},"questions","When email still does not arrive",[36,37],"Check SPF and DMARC configuration next, but remember that published policies are not a delivery guarantee. Sender reputation, authentication alignment, filtering, mailbox rules and remote SMTP behavior are outside an MX lookup.","Compare results from the same resolver and type before diagnosing a discrepancy. Allow for the recorded TTL rather than assuming a fixed 24- or 48-hour propagation period.",[39,40,41],"\u002Fspf-checker\u002F","\u002Fdmarc-checker\u002F","\u002F",1792661399015]