Yes. You can verify any @Eff.org address in real time with a direct SMTP handshake that provides 99.7% accuracy. Eff.org is operated by Electronic Frontier Foundation, runs 1 mail server, enforces 3 of 3 authentication standards, and is currently responding to SMTP.
Every check returns one of three clear outcomes so you know exactly what to do with the address.
The mailbox exists and accepts mail. Send with confidence, the address is deliverable.
The mailbox does not exist, is disposable, or will hard-bounce. Remove it to protect your sender reputation.
The server is catch-all or greylisting, so existence cannot be confirmed. Send selectively and watch engagement.
eff.org publishes 1 MX record. The primary mail exchanger is eff-org.mail.protection.outlook.com, hosted by Microsoft 365, and it is currently reachable and answering SMTP. Mail is routed through these servers in priority order, lowest number first.
| Priority | Hostname | IP | Status |
|---|---|---|---|
| 0 | eff-org.mail.protection.outlook.com | 52.101.50.13 | Reachable |
220 SA2PEPF000015CC.mail.protection.outlook.com Microsoft ESMTP MAIL Service ready at Wed, 3 Jun 2026 06:10:39 +0000 [08DEBC9DC9BE7628]Yes. eff.org is a valid email domain, operated by Electronic Frontier Foundation. Addresses are persistent and real mail reaches a genuine recipient. Individual mailboxes still go stale, so verify each one before you send.
A live SMTP handshake connects to Eff.org's mail server and asks whether the mailbox exists using the RCPT TO command, without ever transmitting a message. The recipient never sees the check.
Each address runs through 30+ checks including SMTP existence, catch-all detection, role-account filtering, and disposable matching. The same engine has verified billions of addresses since 2012.
Every unverified address is a gamble. Here is what happens when you skip verification and mail a list that has not been cleaned.
People leave companies. Verification flags eff.org mailboxes deactivated since you collected them.
Expired or full eff.org inboxes hard-bounce. A live SMTP check catches them before you hit send.
Low bounce rates keep you trusted by eff.org mail servers and the major mailbox providers.
Verified contacts mean your CRM, lead scoring, and routing all run on addresses that reach a person.
Eff.org is Electronic Frontier Foundation, registered through GANDI SAS and first seen Oct 9, 1990.
Eff.org is Electronic Frontier Foundation, classified as corporate email running on Microsoft 365. It operates 1 mail server and currently accepts SMTP connections.
When verifying eff.org addresses, the checker connects directly to Microsoft 365 over SMTP. With 3 of 3 authentication standards in place and SMTP currently responding, verification results for this domain carry high confidence.
Upload a CSV or TXT list of Eff.org addresses to the bulk email verifier. Every address runs through a live SMTP handshake plus catch-all, role-account and disposable detection, and you download a clean list when processing completes. For real-time checks at signup, use the real-time email verification API.
CSV or TXT with one email per line. No formatting needed.
Each Eff.org address is checked with a live server handshake.
Get a verified list with status codes, risk flags, and catch-all detection.
Pay as you go. No subscriptions, and credits never expire.
Everything about verifying email at this domain.
Yes, eff.org is a valid corporate email domain operated by Electronic Frontier Foundation. Addresses on this domain are persistent and reach real recipients.
No, eff.org is not a disposable or temporary email provider. It is classified as a corporate email domain and provides persistent email addresses.
eff.org uses Microsoft 365 for its mail infrastructure.
Yes, provided recipients have opted in. Always verify eff.org addresses before sending to avoid bounces and protect your sender reputation.
Enter any @eff.org address in the email checker above. The system performs a real-time SMTP handshake to confirm whether the mailbox exists, with no email ever sent.
Upload a CSV or TXT list to the bulk email verifier. Every address runs through 30+ checks including SMTP existence, catch-all detection, role-account, and disposable matching. Processing time depends on list size.
99.7% accurate using a direct SMTP handshake with eff.org's mail servers, the same engine that has verified billions of addresses since 2012.
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