Key takeaways
- Hard bounces are permanent; remove the address and never send to it again.
- Soft bounces are temporary; retry a few times, then stop.
- Blocks point to your sending setup or reputation, not to the list.
- Checking addresses before a send prevents most hard bounces.
What is the difference between a hard and a soft bounce
A hard bounce is a permanent refusal and a soft bounce is a temporary one. The bounce message usually says which: mail servers use reply codes starting with 5 for permanent failures and 4 for temporary ones.
The difference decides what you do next. A hard bounce will fail again every time, while a soft bounce may go through tomorrow.
What are the common hard bounce causes
Most hard bounces come from addresses that were never right or are no longer right. Cold lists are especially exposed because nobody on them has confirmed their address to you.
- The address was guessed from a pattern the company does not use.
- The person left, and their mailbox was closed.
- The address was mistyped when it was copied or imported.
- The company changed its domain after a rebrand or merger.
- A catch-all server accepted the message at first, then rejected it later.
Why are emails bouncing back with a block message
Emails bounce back with a block message when the receiving server does not trust the sender, whatever the address. The message often mentions policy, reputation, spam or authentication.
Common reasons are missing or broken SPF, DKIM or DMARC records on your domain, a new domain sending a lot at once, a run of earlier bounces or complaints, or content the filter dislikes. Removing addresses will not fix a block; the fix is in your domain settings and sending habits, usually with help from whoever runs your email.
How do you fix email bounces on your list
Fix bounces by sorting them by kind and acting once, then making the change stick across every tool. A bounced address that comes back in next month's import undoes the work.
- Hard bounces: remove the address and add it to your suppression list.
- Person left: find who now holds the role and start again with them.
- Soft bounces: retry over a few days, then remove if they keep failing.
- Blocks: check your domain's authentication records and slow your sending.
- Catch-all bounces: lower the trust on other addresses at the same domain.
How do you stop bounces before you send
Stop bounces before sending by checking how sure you are of each address and how old the list is. A confidence score, a catch-all flag and a recent date on the role tell you which rows are safe.
Send a new list in small groups first and read what comes back before sending the rest. If the first group bounces badly, stop and check the source.
Where Pebbles Ai fits
- CapabilityProspecting & customer recordsLeads from Find fresh leads carry a work email where found, with a confidence score and a catch-all flag, so you can leave uncertain addresses out of a send. Pebbles Ai makes no deliverability promise.
- CapabilityOutreach contentTemplate send delivers to a segment of the Pebbles Ai CRM, which is in Beta, through your own Gmail or Outlook mailbox and always asks for approval, so bounce notices come back to an inbox you already watch.
Common questions
Can a bounce hurt future emails?
Yes. Mailbox providers notice when a sender keeps hitting addresses that do not exist, and that can push later messages towards spam or block them.
Should I try a different address pattern after a hard bounce?
Only if you have evidence for the new pattern, such as another confirmed address at the company. Guessing again risks a second bounce.
Is an out-of-office reply a bounce?
No. An automatic reply means the message was delivered. Note the return date or the alternative contact it names, and keep the address.
About this page. Written by the Pebbles Ai team for people who run sales, marketing and growth. Last updated .
