After more thinking I don't really see a point in this.
After message is leeched you most likely don't want to auto post it anyways. It does not contain your links, so you will need to replace the links and maybe make more adjustments if needed.
Then you can just select all needed messages and press "Post with themaPoster" button.
Edit:
Actually:
2.19
* Added automatic messages saving to .txt files inside "user/messages" folder by section. First time loading after update might take longer if you have a lot of messages (will try to save all).
Edit:
In more details how you can use the files is talked here:
http://poster.freddy.lt/forum/viewtopic ... 988#p26988