How to Find the Domains in an Email List That Can't Receive Mail (Bulk MX Lookup)

Every address on a domain that has no mail server will bounce, and a bulk MX lookup finds those domains in seconds. Paste your list into the bulk MX lookup: each address is cut down to its domain, each domain is looked up once, and the ones that can't take mail (no MX, a null MX, or not registered) are flagged, with their addresses ready to copy out.

Find dead domains in a list →

Find them with the bulk lookup

1. Open the bulk MX lookup.
2. Paste email addresses, domains or a CSV export: up to 100 domains a run, 500 signed in with Google.
3. Press Look up MX records. Only the domains are sent for DNS lookups; the addresses stay in your browser.
4. Read each domain's mail status, MX hosts with priority, and the provider named from the first host.
5. Copy the addresses on domains that can't receive mail, or download the CSV.

Find them by hand

printf "github.com\nstripe.com\ngmial.com\nexample.com\nnotarealdomain-sv-1109.com\n" > domains.txt

while read -r d; do
  mx=$(dig +short mx "$d" | sort -n | head -1)
  rcode=$(dig mx "$d" +noall +comments | grep -o 'status: [A-Z]*' | cut -d' ' -f2)
  echo "$d,${mx:-none},$rcode"
done < domains.txt
# github.com,0 github-com.mail.protection.outlook.com.,NOERROR
# stripe.com,10 aspmx.l.google.com.,NOERROR
# gmial.com,none,NOERROR
# example.com,0 .,NOERROR
# notarealdomain-sv-1109.com,none,NXDOMAIN

We ran this on 8 November 2026 in bash and zsh. Three of the five can't take mail, each for a different reason:

• gmial.com, a common typo of gmail.com, exists and has a web address but no MX record.
• example.com publishes a null MX, 0 ., which RFC 7505 defines as "this domain accepts no mail".
• notarealdomain-sv-1109.com returns NXDOMAIN: the domain doesn't exist.

One edge case: RFC 5321, section 5.1 lets a sender fall back to a domain's own address when it has no MX, the "implicit MX". It's rare for real mail domains, so treat no MX as a near-certain bounce. A typo domain is better fixed than dropped; gmial.com almost always meant gmail.com.

Next step: verify the mailboxes on the domains that work

A working MX record says the domain takes mail, not that jane@ still exists there. Upload the rest of the list at /verify to check every mailbox without sending. The first 100 checks are free with a Google sign-in, no card.

Pro, $39 a month: Unlimited email verification.* Never metered, never cut off. See pricing.

*Fair use: the first 100,000 checks a month at full speed, then slower, never cut off.

More: check if a domain can receive email, null MX records.