when I delete an emails some others get deleted at the same time then i have to search to find them.
Check you have the latest version of eM Client as some users found with older versions they had that issue which was fixed by updating. See the version history page to check.
Also can be related to a eg: sticky del key or the mouse button from other posts with this same issue.
So test another keyboard and/or mouse if updating eM Client makes no difference.