I installed mail spring using snap and launch it. but in the very first beginning step, I get this error:
Could not reach Mailspring… An operation timed out. But I can access to https://id.getmailspring.com/ using my brower and I even created an account.
If you’re using Ubuntu, I’d strongly suggest you use the deb rather than the snap install. Largely, it seems to have fewer problems (because it can integrate better into the rest of the system, which the snap is designed to avoid) but in particular because snaps save all user data along with the snap, so if you ever need to uninstall and reinstall, you’ll lose all your config. (Assuming you get as far as having a config, of course! 
)
Thanks for the answer. I uninstalled the application, downloaded the .deb file from official website and installed it. But still the same problem as before.