It is possible to obscure your communications from those who track patterns of senders/recipients. Instead of emailing directly to each others email addresses, simply up- and download GHOSTPHRASE messages from a public server. For example this one:
4shared. You do not have to enter your personal email address, and several users can share the same account. It works fine with GHOSTPHRASE messages.

There will be another such service with direct up- and download php scripts specific for GHOSTPHRASE messages available by a link from this page soon.