Hello. I am using Win 8.1 on the laptop and on the desktop
Downloaded Windows version of Mailspring and … Installation is unsuccessful 
Download Win version again… still the same problem.
updated OS with the latest updates, restarted the desktop… STILL THE SAME
Downloaded WIN version on my laptop - STILL THE SAME - Installation failed.
Tried to use “Run as Administrator” - STILL THE SAME.
This is rather frustrating
Would appreciate your support in resolving this matter.
Kind regards,
Sorry for the frustration. Windows 8.1 isn’t supported anymore. Mailspring is built on Chromium (via Electron), and Chromium dropped Windows 7, 8 and 8.1 in early 2023; every Mailspring release since 1.14 requires Windows 10 or later, and the installer simply fails on 8.1 rather than telling you why. Windows 10 and 11 (64-bit) are what the current 1.24.x builds support.
If you need to stay on 8.1, the last release built on an Electron that still ran there is 1.13.3, which you can download from the Releases page of the GitHub project (see Can I turn off automatic updates or use an older version? — Mailspring Documentation). Just be aware that old releases miss security fixes and that Google and Microsoft sign-in changes regularly break them, so it’s a stopgap rather than something I can recommend long-term.