What to do about Mailchimp Bounce and List Deletion Warning

So you’ve imported a list of subscribers into Mailchimp and now you see the following message:

Bounce and List Deletion Warning

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.

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.

You may still send to the list without making any changes, however to avoid exceeding thresholds, 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. If you would like to remove the new addresses, you can undo recent imports from the list’s import history page.

What should you do?
The first thing to do is read the message that Mailchimp is providing; you’ll be amazed at how many people fail to read the message and understand the issue. Mailchimp has a reputation to uphold and if Mailchimp customers are sending Campaigns to email addresses where the message will be marked as spam, then this affects Mailchimp’s reputation.

Mailchimp Omnivore is very accurate in determining stale email addresses or those that are likely to mark messages as spam. Clients that contact me with Omnivore highlighted problems almost always have either purchased a list of subscribers or are using email addresses that were attained months or years back (i.e. the list is stale).
There are a few online tools out there that will help clean your subscriber list however the only foolproof means of having a truly ‘clean’ subscriber list is to ensure that every subscriber has recently explicitly agreed to receive your Campaigns. Also ensure that your subscribers haven’t subscribed using role-based email addresses.

Note: We now offer an email list cleaning and verification service. See our Mailchimp site for more.