I want to turn on authentication but get this error: "This sender address is already in use by another Constant Contact account. Please try another address, or contact support if you have another Constant Contact account already using this sender address." We only have one account through DonorPerfect.
I apologize for any confusion this error message may be causing! For authentication, the domain (what you enter after the @ symbol) must be unique. Meaning each domain can only be used in one Constant Contact account. What is the domain you are trying to use? Although you only have one DonorPerfect account, the domain you are trying to use can already be in use by another Constant Contact account.