Mailchimp is very strict when it comes to adhering to email marketing best practice. Omnivore is the system that Mailchimp use to determine whether you are using Mailchimp to send spam EDM (or may be considered a spammer even if you are not).
Getting omnivore warnings and need help?
A hard bounce indicates that Mailchimp is unable to deliver emails to that address (hard bounced email addresses may be viewed in the cleaned section of your list). A large proportion of hard bounces being returned from a sent campaign indicates an old list or a purchased list. There is good reason that Mailchimp is concerned about high hard bounce rates; even if your subscribers agreed to receive your EDM, if you haven’t sent for awhile then subscribers may forget that they subscribed to receive your campaigns and may mark your campaigns as spam (which in turn has negative impacts on Mailchimp domain reputation and quality).
If Mailchimp determines that your hard bounce rate is too hight you’ll see the following warning when logged in to Mailchimp:
When you click to view more details you’ll get a message like that below ehich you’ll need to acknowledge in order to send future campaigns.
We noticed a 15.8% hard bounce rate on your campaign “Example Campaign” that we’ll want to keep an eye on.
There’s no need to worry yet, but we may send additional warnings if the percentage continues to increase.
Internet service providers set strict limits on unsubscribe rates, undeliverable mail, and abuse complaints, which we have to abide by as an email service provider. Our automated abuse-prevention system, Omnivore, uses these limits to help determine when it’s necessary to issue a warning.
If high hard bounce rates continue then Mailchimp will require you to send a reconfirmation campaign.
The best way of reducing the chance of having high bounce rate proportions when you send a campaign is to ensure that you send to your list regularly or else contact me and I can help advise which email addresses will hard bounce before you send your campaign.