mail reminder in auto

i have compare date value with current date

i have created conditional hyperlink with 7 days and 15 days in column J and K respectively

in this column if days is => 7 days than hyperlink will be active else "ok" text is displaying.

now i want send mail to all whose hyperlink is active i.e. if more than 7 days or 15 days

also i want to send mail only one time means after sending mail one time in next day i use macro then already sent mail should not repeat