Sending PM's on reddit

Besides writing content, I'm also testing out some new ways to convert leads and my medium of choice is Reddit.
Anyone with experience can tell me what would be the upper limit of sending the same message to what amount of users?
Currently sending 10 PM's a day on a three year aged account and 5 PM's on a one year old account.
Not sure if I can rev it up a bit or should I leave it like this?

I too would like to know this, so I will give the thread a bump.

me too.. want to try reddit pm. any working pm bot for subreddit members is awsome.

What do you mean a reddit PM bot?

I can do this, if anyone is interested contact me. So We can get a better talk of how to do this .