One of the core ideas in Hiri is that we can make managing emails easier by adding meaning to To and Cc fields. We shift some responsibility to the sender to help you manage your email more easily - by asking the sender to differentiate between the things you need to do (Action) from the things you just need to know about (FYI).
When composing an email in Hiri, you can put the recipient's email address in either Action (To) or FYI (Cc) field. Depending on the field you put them in, the email will land in either their Actionable inbox or FYI inbox.
Action field means that you want someone to do something - you're sending an action or a task. Indeed, if you put someone in Action, you'll be able to enter a task or a question for that person. Usually, you'll want to send higher priority mails as Actionable.
FYI field means that you just want someone to know about something and no action is required. So these are mainly informational emails. By the way, it's perfectly OK to send an FYI only email - simply put all the recipients in the FYI field and leave Action blank.
You can also mix and match - put some people in Action and some in FYI. For example, people that work on a certain project you'll want to put in Action field, whereas the people that should just be kept in the loop could be in the FYI field.
Actionable inbox is meant to work as your main work inbox. These are the mails that have some action in them and that you need to act on.
All the mails where you were in the Action/To field sent from other Hiri users will land in this inbox. Also, all the replies from people who you put in Action field will land in this inbox.
This inbox is where you would spend the most of your work day and which should be checked more frequently than the FYI inbox. But don't check it too frequently since that's also a bad habit!
FYI, for your information inbox contains all the emails from people who put you in FYI field when they sent the mail. Also, all the replies from people you put in FYI will land in this inbox.
Mails in this inbox don't have a discernible action - they are about stuff you need to keep an eye on, or be aware of. This inbox needn't be checked too frequently.
What about recipients that don't use other email clients?
If your recipients don't use Hiri, Action and FYI work exactly like To and Cc. But if you add a task to an email, the people using other email clients will be able to see the task in the email content.