What is Sisimai ?

Sisimai is a library that decodes complex and diverse bounce emails and outputs the results of the delivery failure, such as the reason for the bounce and the recipient email address, in structured data. It is also possible to output in JSON format.

The latest stable version is Sisimai v5.0.0 , released on Friday, 2 Feb, 2024. It is only available from GitHub (Perl version) or GitHub (Ruby version). Currently, v4.25.16 is available for download from CPAN and RubyGems.org.

Decode Bounce Emails


Sisimai is a library to decode bounce mails for UNIX mbox format files and those in Maildir/ directories.

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Detect Bounce Reasons


Sisimai can decode 34 bounce reasons, including common errors such as "userunknown", "mailboxfull", and "rejected".

Details

Data Structure


The data of bounce emails decoded by Sisimai is structured and can also be output in JSON format.

Details

70 Decoding Engines


Sisimai can decode bounce emails from open-source MTAs, commercial MTAs, email appliances, and well-known email services.

Details

vs. bounceHammer


In the summer of 2014, the Perl version of Sisimai(pronounced as 'shi-shi-mai') was developed to solve several critical problems with the decoding accuracy of bounceHammer, including: Inability to decode multiple bounces in a single email, Large number of dependent modules, some of which are no longer maintained, Inability to work with Perl 5.16 or later.

Sisimai Sisimai is now about 2.2 times faster than bounceHammer and has twice the decoding accuracy. The Ruby version of Sisimai was released on February 3, 2016.

On February 2, 2024, the 10th anniversary of the release of Sisimai, Sisimai v5.0.0 was released. This version can detect modern bounces, including those caused by domain authentication (SPF, DKIM, DMARC) errors and reputation issues.

Analytical Precision Ratio

100%

59%

The Speed Of Decoding 1000 Emails

1.5s

4.24s

Detectable Bounce Reasons

34

19

The Number Of MTA/MSP Modules

70

15

Dependent External Modules

2

24


Can Detect

34

Bounce Reasons

Have

70

Engine Modules

Including

14

Commercial MTA Modules

Only

2

External Modules Required

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The latest version is v5.0.0, released on Friday, 2 Feb, 2024.

Sisimai can run on any OS where Perl or Ruby works, such as *BSD, macOS, and Linux. Sisimai 4.22.5 and later may run with ActivePerl on Windows. .

Perl Version

  • Release version
  • v4: Perl 5.10.1 - 5.24.4
  • v5: Perl 5.26.0 - 5.38.2
  • CPAN
Download

Ruby Version

  • Release version
  • v4: Ruby 2.1.0 - 3.3.0
  • v5: Ruby 2.4.0 - 3.3.0
  • JRuby 9.0.4.0 - 9.1.17.0
Download

Fork on GitHub

  • Development Version
  • p5-sisimai (Perl)
  • rb-sisimai (Ruby)
  • 4-stable, 5-stable
Fork

Support

Sisimai is an open-source library licensed under the two-clause BSD license, so anyone can use it freely. However, Cubicroot Corporation Limited, the developer of Sisimai, offers products and services to support the following:

  • Building an environment for bounce mail decoding
  • Developing scripts around Sisimai
  • Designing and managing a database for storing decoded data
  • Continuous bounce management
  • Migrating from the bounce mail decoding system bounceHammer
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