I will check out whether or not we can add more storage.
This is still brand new here and the 10 message maximum storage may not be permanent. During the day on Wednesday I will see what I can find out. We had to allow over 40,000 posters access to PMs so I don't know if that is the reason for the low amount of inbox storage.
I assure you we will do all we can to make this work as well as it can for you posters.
Thanks, wil.