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Search Domain DNS MX records,email mx records check,mx record lookup

This is free online tool for check MX records (lookup) for domain or check e-mail (and find MX records for e-mail). MX record search going according to RFC recommendation. So just input domain/hostname or e-mail (email) address and push "Go". If you want do dns lookup A and MX a record, fetch dns a mx records, find a and mx records you can use custom domain info tool - it's fecth all DNS records (A,MX, and many others)
RFC2821 (domain for SMTP): Only resolvable, fully-qualified, domain names (FQDNs) are permitted when domain names are used in SMTP. In other words, names that can be resolved to MX RRs or A RRs are permitted, as are CNAME RRs whose targets can be resolved, in turn, to MX or A RRs. Local nicknames or unqualified names MUST NOT be used.
This test will list MX records for a domain in priority order. The MX lookup is done directly against the domain's authoritative name server, so changes to MX Records should show up instantly. You can click "Go" for connect to the mail server, verify reverse DNS records.
A common misconception about the MX preference ordering is that it is intended to increase the chance that mail may be delivered; however, merely having multiple MX records with the same preference provides this benefit.
mx record lookup fast link: or (https://my-addr.com/mx/yahoo.com)

[www.domain.com] it's subdomain of [domain.com]. Thats why [domain.com] can exist but [www.domain.com] not exist and [www.domain.com] can exist but [domain.com] - not.
As usualy mx records don't exist for subdomain [www.domain.com], thats why useful to do mx record lookup and email check for domain (hostname) without 'www'
new window:
yahoo.com (example of lookup)

IP 74.6.143.26
IP 174.6.231.20
IP 274.6.231.21
IP 398.137.11.163
IP 498.137.11.164
IP 574.6.143.25
COUNTRY NAME United States
REGION NAME N/A
CITY Omaha
PROVIDER (ORG) YAHOO-NE1

MX records

MX 1 mta5.am0.yahoodns.net
MX 2 mta6.am0.yahoodns.net
MX 3 mta7.am0.yahoodns.net