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Bulk Email Soft v. Hard Bounce

When an email cannot be delivered to an email server, it's called a bounce. The email server will generally provide a reason for the incident, and Mailchimp uses those reasons to determine how to treat that email address. We categorize bounces into two types: hard bounces and soft bounces.

In this article, you’ll learn about hard and soft bounces in Mailchimp.

Things to know

  • Mailchimp cannot predict whether or not an email will bounce.
  • The receipts for your bounces will be available in your email reports for 30 days after the email is sent.
  • Different internet service providers (ISPs) bounce email messages based on their own rating systems and definitions.

Hard bounces

A hard bounce indicates a permanent reason an email cannot be delivered. In most cases, bounced email addresses are cleaned from your audience automatically and immediately. Cleaned addresses will be excluded from all future campaign sends. Here are some common reasons an email may hard bounce.

  • Recipient email address doesn't exist.
  • Recipient email server has completely blocked delivery.


There are occasionally cases in which valid email addresses will hard bounce.

Soft bounces

Soft bounces typically indicate a temporary delivery issue and are handled differently than hard bounces by Mailchimp. When an email address soft bounces, it will immediately display as a soft bounce in the campaign report.

If an email address continues to soft bounce in additional campaigns, the address will eventually be considered a hard bounce and cleaned from your audience. We'll allow seven soft bounces for an email address with no subscriber activity and up to 15 soft bounces for contacts with previous subscriber activity before converting a soft bounce into a hard bounce. While there are many reasons an email address may soft bounce, these are some common reasons this could happen.

  • Mailbox is full (over quota).
  • Mailbox is not configured correctly.
  • Mailbox is inactive.
  • Recipient email server is down or offline.
  • Recipient email server has been sent too many emails during a period of time.
  • Email message is too large.
  • Domain name does not exist.
  • Email message blocked due to content.
  • Email message does not meet the recipient server’s policies.
  • Email message does not meet the recipient server’s DMARC requirements for authentication.
  • Email message does not meet the recipient server’s anti-spam requirements.
  • Email message does not meet the recipient server’s anti-virus requirements.
  • Email message does not meet the recipient server’s sender requirements.
  • Email cannot be relayed between email servers.
  • Email cannot be relayed for unknown reasons.