winSPMBT PBEM - Extracting map

[low_bidder]

Look on the Shrapnel site. IIRC, you can only rename a PBEM file and open it in the Editor if the security is set to low, OR after the game is over. If you don't want to play it out, just hit the End of turn button and then zip and send. If you co-ordinate with your opponent, this can be done in a few hours.
Somewhere Shrapnel has the post on how to do this.