Sendmail

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Open-source mail transfer agent

title: "Sendmail" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["message-transfer-agents", "free-email-server-software", "free-software-programmed-in-c", "email-server-software-for-linux", "1983-software"] description: "Open-source mail transfer agent" topic_path: "technology/operating-systems" source: "https://en.wikipedia.org/wiki/Sendmail" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Open-source mail transfer agent ::

::data[format=table title="Infobox software"]

Field	Value
name	Sendmail
logo	Sendmail.org_small_logo.gif
logo size	214px
screenshot
author	Eric Allman
developer	Sendmail Consortium, Proofpoint, Inc.
released
latest release version	8.18.2
latest release date
operating system	Cross-platform
language count
genre	Mail transfer agent
license	Sendmail License
website
replaces	delivermail
::

::callout[type=note] the mail transfer agent ::

A descendant of the delivermail program written by Eric Allman, Sendmail is a well-known project of the free and open source software and Unix communities. It has spread both as free software and proprietary software.

Overview

Allman wrote the original ARPANET delivermail which shipped in 1979 with 4.0 and 4.1 BSD. He wrote Sendmail as a derivative of delivermail in the early 1980s at UC Berkeley. It shipped with BSD 4.1c in 1983, the first BSD version that included TCP/IP protocols.

In 1996, approximately 80% of the publicly reachable mail-servers on the Internet ran Sendmail.{{Cite web |author=D. J. Bernstein |url=http://cr.yp.to/surveys/smtpsoftware.txt | archive-url=https://ghostarchive.org/archive/20211024/http://cr.yp.to/surveys/smtpsoftware.txt | archive-date=2021-10-24|title=Internet host SMTP server survey |date=1996-11-27 More recent surveys have suggested a decline, with 3.64% of mail servers in March 2021 detected as running Sendmail in a study performed by E-Soft, Inc.{{Cite web |url=http://www.securityspace.com/s_survey/data/man.202102/mxsurvey.html | archive-url=https://ghostarchive.org/archive/20211024/http://www.securityspace.com/s_survey/data/man.202102/mxsurvey.html | archive-date=2021-10-24|title=E-Soft MX survey |website=securityspace.com |publisher=E-Soft Inc. |date=1 March 2021 |access-date=21 March 2021 |url = http://www.mailradar.com/mailstat/ |title = Mail Radar survey |url-status = dead |archive-url = https://web.archive.org/web/20071213001115/http://www.mailradar.com/mailstat/ |archive-date = 2007-12-13 |access-date = 2015-08-19

Allman designed Sendmail to incorporate great flexibility, but it can be daunting to configure for novices.{{Cite web |url=http://www.sendmail.org/doc/sendmail-current/doc/op/op.pdf |title=Sendmail Installation and Operations Guide |first1=Eric|last1=Allman |first2=Claus|last2=Assmann |first3=Gregory Neil|last3=Shapiro |archive-url=https://web.archive.org/web/20081203001718/http://www.sendmail.org/doc/sendmail-current/doc/op/op.pdf|archive-date=2008-12-03 |access-date=2009-07-28

Sendmail supports a variety of mail transfer protocols, including SMTP, DECnet's Mail-11, HylaFAX, QuickPage and UUCP. Additionally, Sendmail v8.12 introduced support for milters - external mail filtering programs that can participate in each step of the SMTP conversation.

Acquisition by Proofpoint, Inc.

Sendmail, Inc was acquired by Proofpoint, Inc. This announcement was released on 1 October 2013.

Security

Sendmail originated in the early days of the Internet, an era when considerations of security did not play a primary role in the development of network software. Early versions of Sendmail suffered from a number of security vulnerabilities that have been corrected over the years.

Sendmail itself incorporated a certain amount of privilege separation in order to avoid exposure to security issues. , current versions of Sendmail, like other modern MTAs, incorporate a number of security improvements and optional features that can be configured to improve security and help prevent abuse.

History of vulnerabilities

Sendmail vulnerabilities in CERT advisories and alerts:

The UNIX-HATERS Handbook dedicated an entire chapter to perceived problems and weaknesses of sendmail.

Implementation

As of sendmail release 8.12.0 the default implementation of sendmail runs as the Unix user smmsp | title = Sendmail release notes | url = http://www.sendmail.org/documentation | archive-url=https://ghostarchive.org/archive/20211024/https://www.proofpoint.com/us/products/email-protection/open-source-email-solution | archive-date=2021-10-24 | work = sendmail.org | publisher = The Sendmail Consortium | access-date = 2009-08-30 — the sendmail message submission program.

Notes

References

— This is the Sendmail "bible" containing 1308 pages about Sendmail. It is also known as "The Bat Book", because of the picture on its cover. The 1st Edition was published in November 1993.
— A companion to sendmail, 3rd Edition, this book documents the improvements in V8.13 in parallel with its release.

References

"Release Notes".
(October 1, 2013). "Proofpoint, Inc. Acquires Sendmail, Inc.". [[Proofpoint, Inc.]].

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::