Know-How Exchange : E-Marketing

Hi,
Here is what I want to do, and it seems like this is implied by the word ‘campaign’, but not sure:

I want to have a series of emails on different subjects (a particular subject may have 3, 5 or 10 emails) and when I have a new customer/prospect, I assign them to one of the series of emails, or they respond to an offer to receive the emails, which are sent off at intervals predetermined by me. Recipients are each on their own schedule based on starting time, with the clock starting when their name is placed in the system, either by them through their direct response or by me because the are already customers.

Is this the default meaning of a campaign? The references that I have seen are unclear, with the meaning seeming more like bulk mailing to many people at the same time.

I need all the functionality necessary to do such a campaign, including opt-in, out, users may sign in and change their info, possibly click through monitoring etc.

I do not have need for much more functionality beyond this, as I do not have a marketing staff, so full CMS software is not necessary.

I have looked at Sugar CMS, but in their demo I could not seem to find a way to do personalized starting times staggered by start time. SugarCMS was also much more fully featured than I needed.

Is there a simpler or better software system as competitively priced as SugarCMS (read: free) that will do what I need?
Will SugarCMS do it, if nothing else exists?
Thanks