Bounces occur when an email can't be delivered to an email address. When an email bounces, it is classified as either a soft or a hard bounce.
In this article, you'll learn about types of bounces, guidelines for bounce limits, and how to handle them.
Types of bounces
Mailchimp recognizes two types of bounces, and we handle them differently. Hard bounces happen when an email can't be delivered. This can be caused by an invalid email address or an unexpected error during sending.
Soft bounces are recognized by the email server, but are returned to the sender because the mailbox is either full or temporarily unavailable.
High bounce rates are often caused by audiences that have gone stale, or addresses that were improperly entered or imported.
Internet service providers (ISPs) have limits for bounces, unsubscribes, and abuse complaints, and Mailchimp is required to enforce these limits. If these rates are too high, it could prompt a warning or suspension on your account.
Bounce rate limits vary between ISPs and email providers, and they change throughout the year based on incoming email volume. Because these limits are variable, and to avoid giving too much information to spammers, ISPs do not publicly release their limits.
How to avoid bounces
If you haven't sent a campaign in a while, reconfirm your audience to keep your contact information up to date. This should help protect your audience from spambots and fake signups that lead to bounces.
Yes. After you send an email campaign with Mailchimp, we track its delivery and clean bounced addresses from your audience. Email campaigns won't be sent to those addresses anymore, but you'll still be able to access them if you need to.
Sometimes hard bounces happen to valid email addresses. If a bounced address has recently engaged with your email campaigns, we won't remove it from your audience right away. The bounce will be noted in the contact's profile and count toward their contact rating as we keep an eye on future activity.
Although we manage bounced addresses for maintenance purposes, Mailchimp is not a contact cleaning service. If you import old or invalid contacts, subscribers who bounced or unsubscribed previously won't be automatically blocked. If an email campaign is sent to these addresses, it could lead to a high number of spam complaints, undeliverable messages, or unsubscribes. To avoid these problems, follow best practices when adding or importing subscribers to your audience.