AAMC Traffic Rules For the April 15th Deadline

I am still waiting for financial aid offers from most of my admitted schools. I know the traffic rules say by April 15th to drop all but 3 offers. I have also heard that this is just a suggestion, not a requirement, but I cannot find any official AAMC sources that say its a suggestion. Can anyone clarify or provide official links where it says its a suggestion. And is the process as simple as sending an email to a school?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Tags: Pre-Medical (MD) Source Type: forums