Email inbox, "Append to" setting bug

Hello, i have searched numerous forums for answer or information to no avail.

If i understand correctly leaving “Append to” field empty in Setup/email account, should not append incoming emails to any DocType. Email account is created for the email inbox purpose only. However all incoming emails are appended to Communication. To my understanding this might be a bug. Or am i missing something ? Please help. I appreciate all the answers.