A soft bounce is caused by a number of different things. The recipient’s mailbox could be full, the server could be offline, or the message being sent could be too big.
There are ways to minimize the probability of soft bouncing during campaigns. Those include:
- Avoid buying mailing lists
- Give users the ability to update their email addresses
- Include a prominent unsubscribe link in all of your emails
- Make sure email addresses for formatted correctly
- Test messages on major email servers before sending them to your list
During a campaign, soft bounces are often recorded to let email marketers know that the email address is still valid, though it is unavailable at the moment. Some email marketing services will automatically resend soft bounces to see if the problem resolved itself.