Rated 5 out of 5 stars

Great addon! Wonder if there is a way to set it as the Start Page. That will be very useful.

This review is for a previous version of the add-on (2.0). 

This add-on replaces the start page, so yes, it's possible (in fact, it's mandatory). If that's not happening for you, please file a bug here: https://bitbucket.org/squib/mail-summaries/issues/new