Has the exec team considered getting a re-direct on the PO Box, ie mail with marked "Membership Application Form" or addressed the Recruitment officer, to go to Carlo or the first step in whatever the membership process is ??
Or what about a fax service - Surely you can pay per fax with a small establishment fee ?? Get the fax re-diverted to an e-mail address so the process can start being kicked off, meanwhile the original fax can be posted or whatever is required for the signiture thingy requirements ???
Just some suggestions.......