Reverse DNS

First, my question, and then a tiny rant.   I need to get my reverse DNS configured so that my mail stops being returned as likely spam from any number of places.   When I last called in I was met with complete confusion.  Can I get this done somehow?

Also....

Why in the world can customers not set up their own reverse lookup?   The interface to manage my services through Comcast is so antiquated and absurd that it's just infuriating.  I'm not the sort of guy that sends out rants, or blows up on the phone or whatever.  But I've been a customer with Comcast business for somewhere around 13-15 years and there has been almost no change in actual functionality.  When I view my internet services I have three options, "Download Norton," "View Static IP's," (yeah, it's a list of my addresses) and "Troubleshoot" (which takes me to an internet support tool to presumably help me figure out, using the internet, why my internet isn't working).  C'mon guys.  That I have to post to a forum to get RDNS is absurd.  Or send an email even.  If you need someone to write an interface to let your customers do this, let me know.  I'll name that tune in 10 lines of perl (disclaimer: they may be very long lines).