Tessian

What It Does

Tessian is an email security product, now part of Proofpoint. It uses machine learning to detect and prevent accidental data loss, misdirected emails, and email-based threats — for example, flagging when someone is about to send sensitive data to the wrong recipient. It is a general cybersecurity tool rather than legal-specific software, though law firms handling confidential client data use it to reduce email data-leak risk.

What We Found

Tessian was founded in 2013 in London (with a Boston office) and raised funding from Sequoia, Accel, March Capital, and Balderton. In October 2023 it agreed to be acquired by Proofpoint, and the deal closed in December 2023; Tessian’s technology has since been folded into Proofpoint’s email-protection line. Its standalone LinkedIn page is largely historical following the acquisition.

What We Haven’t Verified

• Current product roadmap and naming under Proofpoint ownership.
• Acquisition price — not disclosed.
• Current headcount — post-acquisition figures vary widely across sources.

Company Info

• Sector: Email security / cybersecurity (used in legal); product of Proofpoint
• Founded: 2013
• HQ: London, UK (with Boston office)
• Status: Acquired by Proofpoint, December 2023