Did you have subscribers with a history of bouncing? Or have received a year worth of emails, but never clicked?
Cleaning your email list is at the cornerstone of email marketing performance.
Not only will this help your open rate, but it will also decrease your monthly cost.
We use an in house formula, to determine the metrics of what each account's list cleaning parameters should be. A minimum of three parameters are used in each account. These can also vary based on iOS updates.