I noticed a compliance warning yesterday that I haven’t seen before (this was a Mailchimp Pro account so it may be unique to Pro subscribers). It’s interesting that Mailchimp notes that it will send to a subset of subscribers and determine the outcome (i.e. how many complaints or bounces there are) and then send any Campaigns to further subscribers once the quality of the subset has been determined.
If you need help in determining which of your subscriber email addresses may no longer be valid then please contact me. Below is the error message received upon import of a list by my client.
Mailchimp’s artificial intelligence system, Omnivore, automatically scanned your recent import. Omnivore flagged the list for having a large number of addresses that may cause complaints, high bounce rates, or blacklistings. Our research shows that this can lead to increased abuse and complaint rates. This is known as a ‘stale’ list. Stale lists are often older lists, and may not have been sent to in some time, collected through supported methods, and/or improperly managed for bounces and unsubscribe requests.
Sending to a stale list will generate undeliverable mail, known as bounces. Stale lists also typically contain spam trap addresses. Sending to spam traps hurts the reputation of the servers used to deliver your content, and can cause further blocks against sending.
Internet Service Providers and email services set limits on the number of emails that report abuse, send to spam traps, and generate high bounce rates. When those limits are exceeded, the sender of the emails can be blocked from further sending.
To resolve this issue, we strongly recommend re-confirming the list through double opt-in methods to ensure that all subscribers on the list expect to receive the content you send.
Keep in mind, you may still send to the list without making changes. If you choose to do this, Mailchimp will slowly send to the list over a period of hours to monitor the bounce and complaint rates. If the rates remain low, we’ll complete sending to the remainder of the recipients. All existing addresses previously sent to through the account, and any addresses collected through our double opt-in process will be sent first.
Please be aware that the new list will be automatically deleted if bounce or complaint rates exceed thresholds. Only the newly imported addresses will be deleted. Any email addresses in the list that you have previously sent to through the account, and any addresses collected through our double opt-in process, will not be removed; you can continue to send to them as usual.
Noting this, we recommend you backup the list data before sending. How can I view or export my list?: http://kb.mailchimp.com/article/can-i-extract-export-or-download-my-list-from-mailchimp
If you would like to reconfirm the list, and you believe that you have permission to contact these individuals on a one to one basis, then you may want to send a reconfirmation email outside of our service so they can opt-in via a double opt-in process. How to Reconfirm a List: http://kb.mailchimp.com/article/reconfirm-your-list
All the best,
The Mailchimp Team