Regarding the emails I (personally) recommend to change the email text. This is easily done in the email language files. Why ? If a user receives the answer in the email he has no need to return to the website.
If a link to turn off the following messages would be added, I as well would send the user back to the site, at least to login properly.
Another idea of an experienced member here was to collect all info and send it once a day, this I as well like very much.