<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by FlyByMike:
If you are pre-paying your card in the hopes of increasing your monthly credit limit, I'm pretty sure that that doesn't work with Amex. Your credit limit is the most you can charge in the month.</font>
I haven't tried doing this with Amex Optima (in which case it probably wouldn't work) but it definitely works with our small business card.