Unintended deletion of any highlighted Gmail message in an emClient Inbox or subset of an Inbox will occur if you go to Tags or to the Mark pulldown and select “None.”
The messages deleted that way within emClient can be found somewhere in the raw Gmail account but have been permanently removed from your emClient view.
I say all users should be notified of this. It is NOT documented anywhere and there are no Warnings when you unintentionally do such deletions. So far emClient does not admit this is an issue much less put it on a list to be fixed.