Well, ultima hasn't got such a big comunity, so I'm sure that if you browse through your cards, there are players who you haven't seen for weeks/months.
Also, don't just ask everyone's GC as you would indeed reach the '40' limit pretty fast. Just delete some you don't see often or never send mails to.
Also don't forget you don't need the GC of your teammates, as you can see a list of their GC and send them mails, chat etc.