Good plugin with chinks

First of all: the plugin works correctly.
My observations are:
– I’ve tried to delete one of my own templates with the result, that ALL of my own templates are deleted
– there is no way to edit an own template (an error is shown: please select a template)
– it is impossible to delete the default templates (why this?)
– after choosing a template in template editor the template is sometimes not shown
– in the list of sent emails is no function to edit, resend or delete one or more emails