Researchers Uncover 12,276-Login Mail Access Combolist Leak

When analysts flagged a file called "MAIL ACCESS 12621 MIX DOMAIN VALID 100" circulating on Telegram, the first step was verifying what it actually contained. Uploaded on March 25, 2026, the file's name promised 12,621 records, but the confirmed count came in at 12,276: email addresses paired with plaintext passwords and the URLs of the login pages they open, organized by domain and marked as tested and working.

What Investigators Found in the "Mix Domain Valid" File

The "mix domain" label means the credentials span logins across a range of different websites and email providers rather than just one target, and "valid 100" signals the seller checked and confirmed every record before posting it. That combination makes this an unusually clean, ready-to-use list rather than raw, unverified scraped data.

What Was Exposed

• Email addresses across a range of domains
• Plaintext passwords, confirmed as working logins
• URLs identifying the specific site each credential unlocks

Why This Matters

Because these logins were pre-verified, they carry more immediate risk than an unchecked dump. Attackers can move straight to credential stuffing other accounts that share the same password, attempt account takeover on the exact sites listed, or use the confirmed email and password pairs as a foothold for identity theft and financial fraud.

How This Kind of Mail Access List Gets Verified

After infostealer malware pulls raw logins off infected devices, sellers typically run automated checker tools against each one to confirm it still logs in successfully. Records that fail get discarded, and the ones that pass, like the 12,276 here, get repackaged into a "valid" batch that commands a higher price on Telegram because buyers know the work of testing has already been done for them.

Check If Your Login Was Part of This Leak

If your email address is one of the 12,276 confirmed logins in this file, an attacker already knows it works. HEROIC's free breach scanner checks your email against more than 400 billion leaked records and tells you right away if you show up. If you get a match, change that password everywhere you've used it and enable two-factor authentication on every account that offers it.