Learn Sendmail's origin as a pioneering open-source mail transfer agent, its Proofpoint ownership, and current commercial and open-source options.
Category
Communication
Pricing
Free open-source MTA, with commercial Sentrion-based support and enterprise features available through Proofpoint, from Free as an open-source distribution; commercial and enterprise pricing available on request from Proofpoint
Verified
Not yet
Last updated
July 19, 2026
Founded
1981
Headquarters
Originally Emeryville, California; now maintained under Proofpoint, headquartered in Sunnyvale, California, United States
Open SourceFreemiumSelf-Hosted
Overview
Sendmail originated in the early 1980s at UC Berkeley as a derivative of an earlier program called delivermail, and shipped with BSD 4.1c in 1983 as one of the first mail servers to support TCP/IP email delivery. It dominated internet mail routing through the 1990s before losing significant market share to Postfix and Exim in the 2000s.
The commercial company behind it, Sendmail, Inc., was founded in 1999 by creator Eric Allman and was acquired by Proofpoint in October 2013 for about 23 million dollars. Proofpoint, now headquartered in Sunnyvale, California, was itself taken private by Thoma Bravo in 2021 and continues to maintain both the open-source Sendmail project and a commercial Sentrion-based offering.
Key Features
Sendmail is a highly configurable, battle-tested MTA that handles SMTP mail routing, address rewriting, and complex multi-domain relay scenarios through its sendmail.cf configuration language, refined over more than 40 years of production use.
It supports extensive third-party milter integrations for spam and virus filtering, and its commercial Sentrion platform builds enterprise features such as dedicated support and advanced routing controls on top of the open-source core.
Pricing
The open-source Sendmail distribution is free to download and self-support, maintained by Proofpoint for the community.
Organizations needing dedicated support or the Sentrion-based enterprise platform must contact Proofpoint directly for custom commercial pricing, as no public list pricing is available for the enterprise offering.
Key Features
Battle-tested SMTP mail routing — Decades of production use handling core SMTP mail transfer and routing on the internet.
Rule-based configuration via sendmail.cf — Highly configurable mail routing and address rewriting through a mature, if complex, configuration language.
Open-source distribution — Maintained by Proofpoint as a free, community-available open-source project.
Sentrion commercial platform — Proofpoint's commercial enterprise email infrastructure platform built on Sendmail technology.
Broad Unix and Linux compatibility — Historically shipped with many BSD and Unix-derived operating systems.
Milter support — Extensive third-party mail filter (milter) integrations for spam and virus scanning.
Sendmail is one of the oldest mail transfer agents (MTA) on the internet, originally created in the early 1980s at UC Berkeley to route SMTP email between servers.
Is Sendmail still maintained?
Yes, the open-source Sendmail project continues to receive periodic maintenance releases under Proofpoint's stewardship as of 2026.
Who owns Sendmail now?
Sendmail, Inc. was acquired by Proofpoint in October 2013, and Proofpoint was later taken private by Thoma Bravo in 2021.
Is Sendmail free?
The core Sendmail distribution is free and open source; Proofpoint's Sentrion-based commercial platform and enterprise support are separately priced.
How does Sendmail compare to Postfix and Exim?
Sendmail is older and more established but has a harder-to-learn configuration syntax, and has lost significant market share to Postfix and Exim in new deployments since the mid-2000s.
How old is Sendmail?
Sendmail originated in the early 1980s, first shipping with BSD 4.1c in 1983, making it roughly four decades old as of 2026.