An Advanced mass email is being received to an account that has multiple personas who have the same email address and one persona is opted out and the other persona is opted in. This happens when the Advanced Mass Email settings are set to send to All Personas.
When a recipient clicks the opt out link on an email, the persona or personas with that email address are all automatically marked as opted out. When a user manually opts out a persona, there is nothing in place that ensures all other personas with that email address are opted out. Users who choose to manually opt out a persona will need to check the other personas on the account and opt those out as well if the email address in question exists there.
Steps to Duplicate
The account must have duplicate email addresses on multiple personas and have one persona opted out and one persona opted in for them to receive this email.
Click the category that the template is stored in
Click Mass Email under the template
Select Advanced Mass Email
Select the category of the query that is going to be used
Select the query
Under the Email Addresses should be pulled from which Persona, select All Personas
Go through Step2 and Step 3 without changing anything
On Step 4, verify this email is going to be sent to at least one persona. Instead of showing this Preview Statistics, it should give you the error message that there are no valid email addresses in the query to be sent, since at least one of the personas is opted out (and all of the personas have the same email address).