When it comes to rented or purchased lists, you may come across vendors or marketers who say, "This email list is totally opt-in!" This means the people on the list opted in to an email communication from someone at some point in time -- the list provider, for example -- by filling out a form or checking a box to receive more content from that provider.
Rob, you don’t say who ‘booted’ you from using it. A significant GDPR factor is non-profits having to consent/re-consent those on established email lists and experiencing significant proportions of lists being lost because people miss the notifications or are too busy to fill in yet more forms. However, I have found a few using a ‘one-touch’ re-subscription button that takes immediate effect, without the recipient having to do anything else. It would appear that the re-subscription rate is higher, the easier it is to activate. On enquiry, I was told that they were using mail chimp for this.
InfusionSoft is a fully functional CRM and marketing solution created for small and medium size businesses. Comparing it to MailChimp or AWeber is like comparing a Lamborghini to a VW Golf. It provides highly advanced features for list segmentation, lead scoring and marketing automation. On top of all that, you can integrate all of these features with your optin form using Infusionsoft Tags + OptinMonster.