I have a database-like spreadsheet with a few key columns:
Company (text field)
Agent (text field)
Agent Email Address (valid email address)
Client (text field)
Sent Forms (date field)
Received Forms (date field)
Reminder Sent (text field)

I would like to create a macro that automatically sends an email to the Agent 3 weeks after the Sent date if the Received date is not populated. To avoid sending multiple emails, once an email is sent, the Reminder Sent column should get populated with "yes" and not allow subsequent emails.

The email would use a mail-merge type format so I can say "Dear [Agent], we have not received [Client] forms from [Company]. Please send asap."

Is something like this possible using Excel? I know Access is better for databases but I don't know it very well.
Thanks,
Phillycheese