How many times do you switch your mails from read to unread to treat them later ?
There is no read or unread state on Sandmails.
Instead you simply organize your mails as tasks :
- received for new mails
- to do (for doing it later)
- in progress
Just swipe on your mails to switch between status.
Sandmails is easy to understand to never forget to answer an email or do what it request to.