Sisimai: Mail Analyzing Interface

Release Notes

Sisimai 5.7.1

2026/07/17

Sisimai 5.7.1 has been released. Changes in this version are the implementation of defensive limits on recursive processing and tiny bug fixes. Changes in the Perl version of Sisimai are indicated by Perl at the beginning of each item, changes in the Ruby version of Sisimai are indicated by Ruby, and changes in the Go version of Sisimai are indicated by Go.

And then, Sisimai 5 includes many changes that are not compatible with Version 4, so please check the Perl or Ruby version of your environment before installing or upgrading.

Bug Fixes

  • Go Fix the maximum mailbox size limit from 2TB to 2GB #421
  • Perl Ruby Go Fix a bug where the HELO command was duplicated in the SMTP command detection list.

Attack Mitigation Updates

  • Perl Ruby Go Restricted the maximum MIME nesting level to 64 to handle deeply nested parts safely. #670 #441 #423

Code Improvements

  • Perl Ruby Refactor internal definitions to use constants for bounce reasons, SMTP commands, and Action: values. #672 #676 #677 #443 #447 #448