Where can I find out how my contacts were added to a specific list?
From the Dashboard, go to Reports and click on Contacts to get to Subscription statistics. Select the list you’d like to review the numbers for.
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List statistics
After choosing lists to view, you can define a date range. View subscriptions by source in the How new contacts were added section.
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View unsubscribe reasons in How contacts were deleted.
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If you prefer, switch to list view by clicking on list name in List trends. Daily data is displayed in individual rows with the totals and averages below the table.