When an email is rejected by a subscriber's 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 campaign report. It's a good idea to keep a close eye on your bounce numbers to be sure your campaigns are reaching your subscribers, 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 removed automatically and immediately from the active subscribers and placed in the Cleaned portion of your list. Cleaned subscribers will be excluded from future campaign sends to this list. While there are many reasons an email address may hard bounce, these are some common reasons this could happen.
- Recipient email address does not exist.
- Domain name does not exist.
- Recipient email server has completely blocked delivery.
There are occasionally cases in which valid email addresses can hard bounce or a subscriber could mistakenly unsubscribe and will need to opt back in to your list.
Soft bounces typically indicate a temporary delivery issue to an address 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 list. We'll allow seven soft bounces for an email address with no subscriber activity and up to 15 soft bounces for subscribers 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.