You may mark important emails - use different colours to mark for different reasons e.g. red - business, green home etc.

1. Right click on email, place cursor on Follow Up, select the flag that you wish to for the particular email.

2. You can also flag emails to follow up at a later date, right click email.

3. Instead of flagging the email, click on the Add Reminder.

4. The  flag for follow up box will appear, this allows you to choose a flag and also select a date for follow up.