I have a similar problem, 50% of customers (hundreds) are in the pending state. I followed the best practices. If I subscribe to the email they receive a 10% discount, for this reason many subscribe, but then they do not “read” the second email and therefore do not accept.
Every now and then, manually, I send individual emails to these customers to remind them of the discount and then check their spam. In this way I recover many from the “pending” state. But this manual operation is long.
Mom is it clear to us why many users receive the emails and for many others we end up in spam.
Maybe the [email removed] address is not suitable? Is the subject or the text of the subscription acceptance email not suitable?
How can we send a second email to all “pending” customers?