Creating My Own Yahoo Groups

Hi,

I'm run online social networks and am interested in either having software created or using pre-existing software to duplicated some of the functionality of Yahoo Groups. For those of you familiar with Yahoo Groups, it's an online message board of subscribers who receive messages from members directly to their inboxes. I currently have a group using Yahoo Groups and have 4,000 members. I want to create a platform that essentially does the same thing but can be personalized to my company and branding. I also want to be able to add banner ads to the postings. I'm not sure where to start, if there is software out there that can do this and can be personalized or if I need to find someone who can develop this. Would love your feedback!

Sincerely,
Danielle Scherman
danshells@hotmail.com