Heshan Jayasinghe writes:
I am interested on your project "A Dashboard for Admins/Owners/Moderators".I read your Documentation given about these projectI want to know the path I should follow to contribute your company.
Start by (re)reading the ideas page, paying specific attention to the (new) section "Mentors Are Not Teachers".
Note that there is a lot of competition for this project. (If I'm counting correctly, yours is the 4th inquiry about it.) You will get more attention and are more likely to be accepted into GSoC as you provide more of the planning and design ideas yourself, rather than asking the mentors to do it for you.
By the way, a point of English usage: GNU Mailman is not a company (at least in common use in American English). It is a cooperative project by volunteers.