Dragging an email from email list to folder crashes the application

## Prerequisites
- [x] I have searched open and closed issues for duplicates.

## Describe the bug
I wanted to move a mail to a specific folder. I tried to drag&drop a mail from the mail list (second column) to the folder list (first column), but that instantly crashed the application. I can reproduce the problem 100% of the times.

### To Reproduce

Steps to reproduce the behavior:
1. Open the mail application
2. Pick any mail from the list in the second column
3. Drag it to anywhere in the first column
4. App goes bang!

### Expected behavior
Ideally I would love to be able to move the selected mail to the desired folder, but not crashing would be a good start.

### Logs
I'm happy to share the logs, but how?

## Platform Information

Please check what applies:
- [ ] I'm using the latest version from git that I've manually compiled
- [x] I'm using the latest released stable version

## Additional context
All I wanted to do really was delete a mail. But that's for another ticket.