Two latest incompatible releases (e.g. 2.0.0 and 1.9.0).

Latest release gets all bug fixes, features, etc. Previous incompatible release gets security fixes and fixes for problems that render software completely unusable in certain configurations with no workaround.

• If the vulnerability is specific to Madmail's fork features, please email: omid.zamani.4t@gmail.com.
• If the vulnerability also affects the original maddy project, please email BOTH omid.zamani.4t@gmail.com and the original author at fox.cpp@disroot.org (include "[maddy security]" in the subject).

Otherwise, if it's a minor issue with low impact, you can open a public issue.