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:
https://my-addr.com/mx/
or
https://my-addr.com/mx/[domain_name]
(https://my-addr.com/mx/yahoo.com)