This would add a lot of power to Doit because then OTHER people can put tasks into my system.
For example, I could tell several vendors to email me their price before the deadline. I will tell them they must put this in the subject: "#CarpenterBids ^08-01 !Low @office".
Then I will set the gmail filter to forward such emails to my Doit email.
Then on the deadline 8/1, all the info is waiting for me in Doit. I don't have to forward one by one. That's what computers are for.
Since you already wrote the parsing code for Smart Add, this can create a nice "driver" between my internal system and the people outside.
When I reply to them, I would request that they join Doit for further collaboration. ;)