I'm curious if there exists any field or plugin that would populate a mail list service (like mailchimp) with data submitted from a seblod user form. Would like to send bulk mail to form submitters.
I don't think anything like this exists at present "out of the box". However you could code something yourself with BeforeStore processing and the Mailchimp API in order to take the submitted information and send it to your Mailchimp signup form: