Hard Bounce vs Soft Bounce: What to Do About Each
Hard bounces are permanent, soft bounces are temporary. Learn how to read the codes and the exact action each one needs.
A bounce is a delivery failure reported by the receiving server. There are two families, and they need different treatment.
Hard bounce: permanent
The address does not exist, the domain is invalid, or the server permanently refuses mail. These usually come with 5xx codes.
Action: remove the address immediately. Retrying only hurts your reputation.
Soft bounce: temporary
The mailbox is full, the server is down, or the message is too large. These come with 4xx codes.
Action: retry for a short period. If the same address soft bounces across several campaigns, treat it as dead and remove it.
Blocks are a third case
Some bounces say the message was blocked because of reputation or content. These are about you, not the address. Check authentication, content and complaint rates.
A simple rule set
- 1 hard bounce: remove
- 3 soft bounces in a row: remove
- Block messages: investigate your sending, do not remove the contact
Prevent them
Verification catches most future hard bounces before you send. Use the email checker or the bulk verifier.
Clean your list before you send
Verify 100 email addresses free every month. Plans start at $19.90 a month for 25,000 verifications.