Utilizing Gravity Forms and the Mailchimp add-on you could do something like the following. This is not tested but should get you going down the right path.
-
Create a “subscribe” link in your template that contains the search parameters. (Perhaps the search parameters are captured from the query string. I’m not sure what works best for your use case.) When clicked, this link would bring users to a page with a Subscribe form built using Gravity Forms.
-
In the Subscribe form pre-populate the values of some hidden fields with the search info retrieved from the query string.
-
Connect the form to Mailchimp using the Mailchimp add-on. Pass the search parameters to Mailchimp along with the user’s subscription info.
-
Use Mailchimp to send emails to users. These emails should be generated from the site’s RSS feed. Users should receive the correct feed based on the info passed to Mailchimp when they subscribed.
I have worked with Gravity Forms and Mailchimp in the past and am confident that steps 1-3 are possible.
Step 4 is the part I am the least certain about. Mailchimp allows you to segment and group your email lists to better target people with the info they want. The trick here is matching the correct RSS feed to the correct segment/group and I can’t recall exactly how that would be done.
Depending on the granularity of your search parameters it might be difficult to subscribe users to the feed of their choice.