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| Sendmail | |
|---|---|
 | |
| Original author | Eric Allman |
| Developers | Sendmail Consortium,Proofpoint, Inc. |
| Initial release | 1983; 43 years ago (1983) |
| Stable release | |
| Operating system | Cross-platform |
| Predecessor | delivermail |
| Type | Mail transfer agent |
| License | Sendmail License |
| Website | www |
Sendmail is a general purposeinternetworkemail routing facility that supports many kinds of mail-transfer and delivery methods, including theSimple Mail Transfer Protocol (SMTP) used for email transport over theInternet.
A descendant of thedelivermail program written byEric Allman, Sendmail is a well-knownproject of thefree and open source software andUnix communities. It has spread both asfree software andproprietary software.
Allman wrote the originalARPANETdelivermail which shipped in 1979 with 4.0 and 4.1BSD. He wrote Sendmail as a derivative of delivermail in the early 1980s atUC Berkeley. It shipped withBSD 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.[2] 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.[3] A previous survey (December 2007 or earlier) reported 24% of mail servers running Sendmail according to a study performed by Mail Radar.[4]
Allman designed Sendmail to incorporate great flexibility, but it can be daunting to configure for novices.[5] Standard configuration packages delivered with the source code distribution require the use of theM4 macro language which hides much of the configuration complexity. The configuration defines the site-local mail delivery options and their access parameters, the mechanism of forwarding mail to remote sites, as well as many application tuning parameters.
Sendmail supports a variety of mailtransfer protocols, includingSMTP,DECnet'sMail-11,HylaFAX, QuickPage andUUCP. Additionally, Sendmail v8.12 as of September 2001[update] introduced support formilters - external mail filtering programs that can participate in each step of theSMTP conversation.
Sendmail, Inc was acquired byProofpoint, Inc. This announcement was released on 1 October 2013.[6]
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 ofprivilege separation in order to avoid exposure to security issues. As of 2009[update], current versions of Sendmail, like other modernMTAs, incorporate a number of security improvements and optional features that can be configured to improve security and help prevent abuse.
Sendmail vulnerabilities in CERT advisories and alerts:
TheUNIX-HATERS Handbook dedicated an entire chapter to perceived problems and weaknesses of sendmail.
As of sendmail release 8.12.0 the default implementation of sendmail runs as the Unix user smmsp[7] — the sendmail message submission program.
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