I believe you used to be able to mail direct to them, but now their email directs you to their online form.

https://www.aa.com/contact/forms?topic=CR#/

If you email [email protected] directly, you get this auto response:This is an automated response from American Airlines Customer Relations

Thanks for your e-mail! If you are writing us for the first time, we won’t receive your comments unless you contact us using our online form at aa.com. If you were replying to a prior email from us, make sure you included the full message that you received so that your e-mail can be auto routed to the team member who was helping you.

Thanks again for reaching out to us.

Customer Relations

I will say that when I have used the online form in the past months, they respond within a few days and then you can reply via email to continue any discussion or submit attachments.