Direct Mail Question from a beginner

[Isaac El]

I have been driving for dollars for some time, and have been making my own list, have it in excel.  This is what I am looking to do and wanted to know if any of the more experienced people on here could point me in the right direction.

I have my own list right now, i want to upload that list to a company that sends out the mailers.

1. I can pick the frequency I want to send.

2. I will upload lets say 4 or 5 letters, so for example, if I set my parameters to mail my database once a month, first it would send letter 1, next month it would send letter 2, ect ect.

3.  I will keep adding more and more addresses to my list (and at th esame time, removing some addresses too) When I add an address, I would want it to start with letter 1, then letter 2, etc.

Hope this makes some sense, does anybody know or recommend a company I can use to do this?

-Isaac