Currently there is no to-dos reminder email that goes out on Mondays. Instead, upcoming to-dos are listed in the "weekly summary" email.
The weekly summary email seems like it should contain more high-level information for the week (ex: features and releases assigned) and does not seem like the best place for tactical activity like to-dos. It is easy to miss reminders when they are in the weekly summary email, especially coming back from the weekend.
It would be helpful to receive a regular to-dos reminder email on Monday that specifically lists upcoming to-dos.