MailTester Ninja operates a distributed email-verification network. The domains listed below are the probe domains used by our service, operated by Unlimited & Limited. They are used to perform real-time verification probes only and do not send marketing or bulk email.
Publishing this list keeps our infrastructure transparent and verifiable for mailbox providers and reputation services.
Probe Domains
- nubokado.com
- nubokiyo.com
- nuboshige.com
- nuboyuki.com
- nubotada.com
- nubohide.com
- nubokatsu.com
- nubomasa.com
- nubonaga.com
- nobukado.ninja
- nobushige.ninja
- nobukiyo.ninja
- nobuyuki.ninja
For abuse reports or any enquiry regarding this infrastructure, contact contact@mailtester.ninja.
Privacy & purpose
MailTester Ninja uses no database and stores no email address. Every verification is performed in real time and no personal data is retained, in full compliance with the GDPR.
The service exists to help organisations keep their email lists clean. By confirming that an address exists before anything is sent to it, verification prevents messages to invalid, mistyped or abandoned mailboxes. This matters beyond deliverability: every email sent to a dead address still consumes bandwidth, storage and processing across multiple mail servers, and each of those hops draws power. Cleaning lists upstream removes that waste at the source.
Concretely, verifying before sending reduces unnecessary traffic and server load across the mail ecosystem, protects sender reputation and deliverability, cuts bounce handling, and lowers the needless energy use and CO₂ emissions generated by traffic that would never reach a real recipient. Cleaner data is not only more effective — it is more resource-efficient and more sustainable.