We had a customer report that the functionality related to autoresponders was not working. The interface allowed the user to designate a list or segment to exclude from the autoresponder but those contacts were not being excluded and the settings were not saving. This issue has been resolved with this release effective May 23rd, 2017.
Details about the latest update to the popular Exclude on Send and Import Addon for Interspire Email Marketer. The update has resolved some autoresponder and campaign bugs and added a new feature.
We thought it necessary to take a new and fresh run at developing that feature in an actual addon that is not vulnerable to IEM updates and is compatible with all version 6.0+ and with the most popular existing addons on the market today.
Your current best option is to export the two (or more) contact lists and attempt to merge them into a single excel file. Sort by one of the columns and search for duplicates. It is tedious for certain but it also is a huge time waster.