How to send an eMail on specific dates indicated in 3 different date fields?
You can perfectly use the Rules module for this. Here are the main steps to do so:


You need "a" field related to the "date" your want to do something with (you're fine with that, you already have 3, so repeat what is below for each of the 3 fields).
Create a rules Component  for sending an eMail (specific to the reminder-eMail you want to send).
Create a Rule to trigger the Rules component from Step 2, which typically involves some date offset (like "how long ahead should the eMail be eMailed?").


For a sample of step 2 and step 3 above (in Rules export format), refer to my answer to the question about "Rule to store user&#39;s last post date and scheduled rule based 30 day reminder".

Note: If you're not familiar (enough/yet) with Rules, checkout the 32 (!!!) great, and free, video tutorials Learn the Rules framework.