Subscriptions with definable database fields?

I’ve been building a database of visitors to our site using a Plugin called “Participants Database.” It is very flexible and allows me to define new fields. It does not, however, have an integrated blog subscription option.

I have Jetpack installed, but it appears to me that its subscription option is limited to one field – email address.

I downloaded and have been playing with another plugin called “Email Subscribers.” This has some good features, but also seems to have serious database limitations in that it only includes two fields – email address and name. Without at least first and last name, it isn’t of much use to me.

I want to build a single database where I can define fields that has the capability to send out new blog post notifications AND has HTML plus text email functionality. (By this I mean that you can create both an HTML version and a text version of an e-newsletter such that the recipient’s email client can default to text if HTML is turned off.)

Does such a plugin exit for WP? Thanks.