For email and social you can swipe to the right to save for later or snooze (or tap on the ribbon icon in the message in the upper right).
Cloze will remind you based on the time you set and return the message to the inbox or social feed. You will also see them on your Agenda as they come due in the Today and Upcoming sections or in the Past Due section (if you are not able to take action on the day you set).
To see all of your Saved items tap on the various sections of the Agenda. You will see a reminder ribbon next to each item.
Note: Items you have saved without a due date they are listed under the "Someday" section.