When an email is rejected by a subscriber's email server, it's called a bounce.
This article covers:
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. They're placed in the Cleaned portion of your list.
Cleaned subscribers will be excluded from future campaign sends to this list.
There are many reasons for a hard bounce, including:
- Recipient email address doesn't exist
- Domain name doesn't exist
- Recipient's email server has blocked delivery
Soft bounces usually mean there's a temporary delivery issue.
When an email address soft bounces, it will immediately display as a soft bounce in the email campaign report.
If an email address continues to soft bounce in additional email campaigns, the address will eventually be considered a hard bounce and cleaned from your list.
We allow 7 soft bounces for an email address with no subscriber activity.
We allow 15 soft bounces for subscribers with previous subscriber activity.
There are many reasons for a soft bounce, including:
- Mailbox is full (over quota)
- The recipient's email server is down or offline
- The email message is too large
When tracking your email campaign responses, you'll see hard bounces marked in red, and soft bounces marked in yellow:
What causes high bounce rates
High bounce rates are often caused by lists that have gone stale, or by addresses that were improperly entered or imported.
Internet service providers (ISPs) have limits for bounces, unsubscribes, and abuse complaints. Naturally, we're required to enforce these limits.
If bounce rates are too high, it could prompt a warning or suspension on your account.
Bounce rate limits vary between ISPs and email providers, and they change throughout the year based on incoming email volume.
Because these limits are variable, and to avoid giving too much information to spammers, ISPs do not publicly release their limits or their spam filter criteria.