Error: database disk image is malformed. What to do????

To fix this, it seems like I have to reinstall my eM Client? What will than happen to my calendar, contacts and mails?

I take it you are getting this message when you start eM Client, and it does a database check. Is that correct?

Hello again, Gary;-)
Seems you are my saving angel out here;-)
Yes, that is correct. Right now it started up normal again - do not know why!! - but the downloading messages seems to go and go and not stop.

While you are able to access eM Client, make a backup. Do that now! 

One thing you can do to help prevent problems with the database is to close eM Client a few seconds before you shut down Windows.

Reinstalling eM Client will not fix a malformed database. That is stored separately from the application, so will remain behind after uninstall or reinstall. If you get persistent problems with this, the best option is to delete the database and start again. Deleting the database will delete any data stored in local folders. If your account is setup with IMAP, your emails will be synced with a server, so they will be safe. If you are using a service like GMail or Outlook.com, then the chance is that your contacts and calendar will also be synced online.

Which email provider are you using?

I will make a back up, now!
…and in the future close eM Client a few seconds before Windows. I did not know that one.
Than I will hold the reinstalling for now. How do I know about IMAP?
The one email system I use is eM Client. 

There is small problem with shutdown, but it has been fixed and will be in the next release. Until then, closing eM Client in this way reduces the risk.

To see if you have IMAP, go to Menu > Tools > Accounts. To the right of your account you should see a tab IMAP.

Who is your email provider? (i.e. what is after the @ in you email address)

My IMAP says: imap.domeneshop.no Port 993  Use SSL/TLS
My email adress is torunn@think-management.no

IMAP works by synchronizing your email with a server. So deleting your database, or losing it because it is malformed, will not delete your emails. If all goes wrong, you can just delete the database and start again, and they will be there.

You can always see where the calendar and contacts are in eM Client by looking at the folders.

If they are in Local Folders, they are not synced with a server and could be lost if the database becomes corrupt, unless you have a backup.

So to be safe, make regular backups by using the Automatic Backup option in Menu > Tools > Settings > General > Backup

Thank you, Gary.
I now have a automatic backup.
I see that my calender is in a local folder, as are my contacts. If I understand you right, they will not be lost even if the database becomes corrupt, when I have a backup?
Thank you again, and Marry X-mas;-)

Yes, if the database becomes corrupt you can just restore, and everything including your contacts and calendar will be there.