Hello @MollyM229 ,
An unsubscribe of that size was likely performed by the account owner or a manager uploading a list of contacts for the explicit purpose of unsubscribing them from your account. This can be done for a number of reasons, the most common being:
to maintain unsubscription records when moving to our services from another email service provider
as requested by our Review / Compliance teams due to the inclusion of the particular contacts in your account being non-compliant for any number of reasons
See also:
Enabling advanced email permissions in account
Unsubscribed contacts overview
Review numbers and hours
Constant Contact's Email Permissions Policy
... View more
