Would it be possible to add some features that increase productivity? For example, I would like to see an option for external users to schedule a meeting using my calendar data (or a subset of it if possible).
I am kind of visualizing an option to send a URL which allows the receiver to select a date and time.
An example of this functionality is the meeting scheduler offered by HubSpot.
I believe this would be a feature many users would want. I also think that it isn't too complicated since SmarterMail is already web based.