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. Hard 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, below 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.
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. We will continue to attempt to deliver the email over the course of three days. If the email still soft bounces after we've attempted delivery for those three days, it will remain logged as a soft bounce on the campaign report. If the email can be delivered during the three-day period, we'll remove it from your list of soft bounces for that campaign.
If an email address continues to soft bounce across multiple 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, below are some common reasons this could happen.
- Mailbox is full (over quota).
- Recipient email server is down or offline.
- Email message is too large.