When an email is rejected by an email server, it's called a bounce. There are different types of bounces that depend on the reason the email bounced. These details can be found in your email campaign report. It's a good idea to keep a close eye on your bounce numbers to be sure your campaigns are reaching your subscribed contacts, and that you're abiding by spam laws.
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.
Domain name doesn't exist.
Recipient email server has completely blocked delivery.
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).
Recipient email server is down or offline.
Email message is too large.
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