Email delivery
What is the difference between a hard and soft email bounce?
A permanent failure indicates that delivery is not expected to succeed without a change, such as correcting an invalid address. A temporary failure may reflect a full mailbox, a transient server problem, or rate limits. Read the provider’s diagnostic information instead of treating every failure identically. Repeated retries can turn a manageable issue into unwanted traffic.
How to approach it
- Record the actual delivery response.
- Stop sending to addresses confirmed invalid.
- Retry temporary failures conservatively through the provider’s supported process.
An unknown mailbox response calls for correcting or removing the address. A temporary service outage calls for patience and a bounded retry, not adding the same contact to a second campaign.
Updated September 10, 2026 · By Vibeful Team