I am not worried about spam since there isn't really any avenue for it. If there isn't a GPX/TCX/KML geo file attached to the email, the upload isn't processed

I am not worried about spam since there isn't really any avenue for it. If there isn't a GPX/TCX/KML geo file attached to the email, the upload isn't processed. As a result, I don't expect this to be abused. I think I may just proceed and handle it if it becomes an issue, probably with a simple passphrase in the subject field. I am not using gmail, I actually setup a postfix transport layer, which runs a simple ruby script that just pipes the email through a unix socket to a r receiving server - the server has Resque loaded up and queues up jobs to be handled by my resque workers.