Mailbox provider · Yahoo! JAPAN Mail
How to check if a yahoo.co.jp email address exists
Can you verify @yahoo.co.jp addresses?
PartlyPartly. @yahoo.co.jp accepts any recipient, so a single mailbox can't be confirmed.
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The checker probes @yahoo.co.jp, but it first offers a random address that can't exist. yahoo.co.jp's server accepts it, so the checker returns the real address as risky with "Accepts all addresses" rather than calling it valid. It always checks the syntax, the domain's MX records, disposable domains and role addresses such as info@ first.
Accepts all addressesyahoo.co.jp addresses can't be confirmed with a mailbox check. The domain is run by LY Corporation on its own mail.yahoo.co.jp servers, not Yahoo's yahoodns.net, but on 23 October 2026 its server accepted a made-up recipient at RCPT TO, so real and fake addresses get the same answer. Expect risky results and lean on engagement history instead.
Live DNS snapshot: yahoo.co.jp
Checked 26 October 2026, 05:00 UTCRead from DNS at the time shown and refreshed at most once a day. MX says where mail for yahoo.co.jp goes; SPF and DMARC describe mail sent from it, not whether any one address exists.
- 10
mx3.mail.yahoo.co.jp - 10
mx5.mail.yahoo.co.jp - 10
mx1.mail.yahoo.co.jp - 10
mx2.mail.yahoo.co.jp
v=spf1 include:spf.yahoo.co.jp ~allp=quarantine: meets the requirement and enforces it.
v=DMARC1; p=quarantine; rua=mailto:ymail_dmarc_report@yahoo.co.jpLook up any other domain with the MX lookup or the email provider lookup.
Yahoo! JAPAN Mail at a glance
| Operated by | LY Corporation, Japan, separate from Yahoo Inc.Source: LY Corporation terms of use (Japanese) |
|---|---|
| MX hosts | mx1, mx2, mx3 and mx5.mail.yahoo.co.jpObserved 23 October 2026 (dig MX) |
| Answer to a made-up address | 250 recipient <…@yahoo.co.jp> ok to a made-up recipient, returned at RCPT TOObserved 23 October 2026 (SMTP probe of a made-up recipient, no message sent) |
| Address rule | Yahoo! JAPAN Mail users can create up to 10 free 'safety addresses' (sub-addresses at @yahoo.co.jp) that arrive in the main inbox; up to 30 with the paid security packSource: Yahoo! JAPAN Mail: safety address (Japanese) |
| Inactive accounts | LY Corporation may suspend or delete an account that has not been used for a year or more, unless a service's own terms say otherwiseSource: LY Corporation terms, art. 17.1(4) (Japanese) |
| Postmaster rules | Yahoo! Mail recommends senders adopt SPF, DKIM or DMARC; mail without it may be marked as spam or refusedSource: Yahoo! Mail anti-spam efforts (Japanese) |
Why yahoo.co.jp comes back risky
Our checker offers every domain a random address that can't exist before it asks about yours. yahoo.co.jp's servers accepted that address at RCPT TO, so a yes for a real yahoo.co.jp address carries no information and the checker returns it as risky with "Accepts all addresses". It shares that behaviour with yahoo.com, though the two run on separate infrastructure.
Yahoo! JAPAN Mail is run by LY Corporation, not Yahoo
yahoo.co.jp mail is provided under LY Corporation's terms, not Yahoo Inc.'s. Article 17.1(4) lets LY suspend or delete an account unused for a year or more, unless a service's own terms differ, so a long-dormant @yahoo.co.jp contact can disappear. Don't apply Yahoo.com's 12-month mailbox rules to it.
Yahoo! Mail's anti-spam page recommends SPF, DKIM or DMARC from senders and says mail without them may be marked as spam or refused. Authenticate your sending domain before mailing Japanese contacts.
Safety addresses make one inbox look like many
Yahoo! JAPAN Mail lets each user create up to 10 free sub-addresses called safety addresses, or 30 with the paid security pack, built from a base name and a keyword at @yahoo.co.jp. They all land in the main inbox and can be deleted at any time.
A contact who signed up with a safety address may later delete it, and the address then stops working while the person is still reachable on the main one. If a sign-up address bounces permanently, suppress it, but ask the person for their current address before assuming they have left.
Common questions
- Can you verify @yahoo.co.jp addresses?
- Partly. @yahoo.co.jp accepts any recipient, so a single mailbox can't be confirmed. The checker probes @yahoo.co.jp, but it first offers a random address that can't exist. yahoo.co.jp's server accepts it, so the checker returns the real address as risky with "Accepts all addresses" rather than calling it valid. It always checks the syntax, the domain's MX records, disposable domains and role addresses such as info@ first.
- Is yahoo.co.jp the same as Yahoo Mail?
- No. yahoo.co.jp is run by LY Corporation in Japan and uses its own mail.yahoo.co.jp servers, while yahoo.com mail is received by Yahoo Inc.'s yahoodns.net servers. Both accepted a made-up recipient when we checked.
- Can I check if a yahoo.co.jp address exists without emailing it?
- Not reliably. On 23 October 2026 the server accepted a made-up address at the RCPT TO step, so a mailbox check gets the same yes for real and fake addresses. Verifiers return yahoo.co.jp addresses as risky (accept-all).
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