An unsubscribe occurs when someone clicks an auto-generated unsub link in your email, or the unsubscribe button in their email program.
Mandrill uses a variety of factors to set an account's reputation and hourly quota. One of these factors is the number of unsubscribes relative to your overall sending volume.
After you take steps toward preventing a high number of unsubscribes, your account reputation and quota will adjust automatically based on the new sending patterns.
How Unsubscribes Affect Reputation and Hourly Quota
When ISPs see high unsubscribe rates, they may slow down or even stop accepting your email out of concern that there could be recipient management or permission issues. Like most ESPs, Mandrill actively manages the IP addresses that are used for sending mail through our system. We need to be able to send mail quickly, with as little delay from the receiving servers as possible. The reputation of our IP addresses is paramount to ensuring high deliverability for all of our users.
Reasons for High Unsubscribe Rates
Increases in the number of unsubscribes can mean there are issues with old or stale recipient email addresses, improperly-collected or purchased lists, or irrelevant content.
Reducing or Preventing High Unsubscribe Rates
Remove stale or old email addresses. If you've been sending on a regular basis and tracking opens and clicks, you may consider removing inactive recipients. Inactive recipients are people who haven't opened or clicked your emails in a number of months. This will help eliminate bounces as well as ensure a high-quality list and high engagement. High engagement has the benefit of helping your deliverability as many ISPs use engagement-based filtering, and you ensure that you're only sending content to people who want to receive it and who are more likely to engage with you and your company.
Don't use purchased, rented, or third-party recipient lists. Using a confirmed or double opt-in process is considered an industry best practice, but it's not strictly required. When you use the double opt-in method, you're targeting only those recipients who really want to hear from you.
Double opted-in lists have much higher engagement levels over time which translates to more opens and clicks and fewer spam complaints and bounces. You should always ensure that you're only sending to recipients who have a prior business relationship with you or who have consented to receive emails from you.