How to Check if a Domain Can Receive Email (MX Lookup in 1 Minute)
A domain can receive email if its DNS has MX (mail exchanger) records saying which servers accept its mail. To check, run dig MX example.com on Mac or Linux, nslookup -type=mx example.com on Windows, or use a web lookup. Servers listed: it can receive mail. 0 .: it explicitly refuses all mail. Nothing at all: almost certainly not set up for email.
That tells you about the domain, not about any one address. Whether jane@ exists at that domain is a separate check.
Run the lookup
Mac or Linux
$ dig +short MX gmail.com
5 gmail-smtp-in.l.google.com.
10 alt1.gmail-smtp-in.l.google.com.
...
Windows
> nslookup -type=mx gmail.com
gmail.com mail exchanger = 5 gmail-smtp-in.l.google.com
...
In a browser
Our domain lookup shows MX records plus SPF, DMARC and who hosts a domain's mail. Change the domain in the address bar to check another.
Read the answer
| Result | Meaning | Treat addresses there as |
|---|---|---|
One or more servers, e.g. 10 mx1.example.net. |
Domain accepts mail | Check each mailbox |
0 . |
Null MX: domain accepts no mail (RFC 7505) | Invalid |
| No MX, but the domain has a website | No mail setup; senders may try the web server | Almost always invalid |
Domain doesn't exist (NXDOMAIN) |
Nothing there at all | Invalid |
The numbers before each server are priorities: lower is tried first. Several servers at different priorities are backups, not separate mailboxes.
example.com is a handy test case: when we checked on 11 October 2026 it published a null MX (0 .), the clearest possible "no mail here". We cover null MX in detail in null MX records.
What about "no MX, but an A record"?
The SMTP standard (RFC 5321, section 5.1) says that if a domain has no MX record, a sender should try its A or AAAA address as an "implicit MX". So technically a domain with only a website might receive mail. In practice, website hosts rarely run a mail server on port 25, and a list address on such a domain is a strong bounce candidate.
What the MX host tells you
The MX host name usually reveals who runs a domain's mail:
| MX host contains | Mail is hosted by |
|---|---|
google.com, googlemail.com |
Google (Gmail or Google Workspace) |
mail.protection.outlook.com |
Microsoft 365 |
olc.protection.outlook.com |
Outlook.com consumer mail |
yahoodns.net |
Yahoo (including AOL and some ISPs) |
mail.icloud.com |
Apple iCloud |
pphosted.com, mimecast.com |
A security gateway in front of the real host |
Useful context, with one warning: a company on Google Workspace or Microsoft 365 is still a business domain. Hosting doesn't make acme.com a free email provider. See business email vs personal email.
What an MX check doesn't prove
- That a mailbox exists.
left-the-company@acme.comis on a domain with perfectly good MX records. - That mail will be accepted. Some domains accept every address (catch-all); see what is a catch-all domain.
- That mail will reach the inbox. That depends on your sending reputation and authentication.
The next step after MX is the mailbox check: connecting to the server and asking about one address, without sending anything. We explain that in check if an email is valid without sending.
Checking every domain in a list
Doing MX lookups by hand works for a handful of domains. For a list, drop the CSV into our free list health check: it looks up every domain, flags the ones that can't receive mail, and also catches typo domains (gmial.com), disposable domains and duplicates, with no signup. To check every mailbox, the paid plan does it for the whole file.
Common questions
How do I check if a domain accepts email?
Look up its MX records. On Mac or Linux run dig MX example.com, on Windows nslookup -type=mx example.com, or use a web lookup. If the domain lists one or more mail servers, it can receive mail. If it publishes a null MX (0 .), it explicitly accepts none.
What does it mean if a domain has no MX record?
Under the SMTP standard, a sender falls back to the domain's A or AAAA record and tries to deliver there. In practice most domains with no MX record aren't set up for mail, and many receiving systems treat them as unable to accept it.
Does an MX record mean an email address exists?
No. It means the domain can receive mail. Whether a particular mailbox like jane@ exists is a separate question, answered by asking the mail server in an SMTP conversation, which is what a mailbox verifier does.
What is a null MX record?
A record of the form '0 .' defined in RFC 7505. It tells senders the domain accepts no email at all, so they can fail immediately instead of retrying. example.com publishes one.
Check your list before you send
Real mailbox checks over SMTP, and nothing is sent to the address. Sign in with Google and your first 100 email checks are free, no card. Plans for bigger lists are on the pricing page.