Email list hygiene is definitely key to sender and deliverability scores. It doesn’t matter if your list is optin or not. Everyone needs to keep their lists clean. Here are a few myths that I think you should avoid at all costs.
Since Google banned payday loan advertising, we have seen a rise in the size of databases we clean and have been approached by many payday loan companies for advice in email deliverability. Many have been out of the email marketing game and have to re-learn everything they knew 5 years ago. This article may help.