@tgallag
I have gotten this error every single time for years. Whether or not I shut down the computer makes no difference. If I only close eM Client and leave everything else running, I still get the error.
If you are closing eM Client and “waiting a few seconds” before reopening the program and still getting checking for errors on startup, then that would suggest your mail database is still corrupted somewhere and has not been 100% repaired so just keeps popping up to check for errors all the time.
So would next suggest if you have an eg: IMAP, Exchange, Office 365 or iCloud (Non POP) type account, to remove your account in eM Client and re-add as new via either the automatic email wizard or manual option depending on your specific server requirements. That normally will fix that.
If you have a POP account, then create a folder called eg: Old Mail down in “Local Folders” at the bottom left of eM Client, and then drag / move all your POP messages and folders under Old Mail. Once you are certain they are all there, remove your account and re-add as new. Then drag / move all your old mail and folders back up to your new POP account.
Note:- Before removing your account, backup eM Client via "Menu / Backup. You can see when the backup is complete via “Menu / Operations”.
If that still doesn’t fix it, close eM Client and uninstall the program and “Don’t delete the database” when asked on uninstall. Then re-download eM Client from the Release History Page and reinstall.
Next if that still doesn’t fix it make sure you are using the latest V8.x or 9.x from the Release History Page link above depending on what your license provides. Could be you have an older version of eM Client that needs updating.
Also do all your OS Security patches and updates. If you have Windows 10/11 (22H2) is the latest update. If you have Mac suggest you have updated to “Monterey OS”. Both work fine for me.
Lastly if still a problem, then you have “some other program installed locally on your computer” on startup which is interfering with eM Client in some way. So you would next need to next to troubleshoot your computer by eg: Disabling all background non os tasks and reboot so you have a normal os startup. Then try eM Client again. That should normally fix it. You then enable those background / startup programs one at a time and reboot in between till you find what program is interfering.