Email & SMTP · 2 min read
Bounce Classification Codes and Definitions
What bounce classifications are
When an email can't be delivered, the receiving server returns an error. FunnelStreams groups those errors into classifications so you can see whether the problem is the address, your content, your domain setup or your sending reputation.
Don't troubleshoot from the SMTP code alone. Read the classification and the full bounce message together.
Where to find them
- Email statistics: open a campaign's statistics and click Bounced to see each contact, the classification and the message.
- Conversations: a failed email shows the error on the message.
- Contact record: the email field shows when an address is invalid or has bounced.
What each type means and what to do
| Classification | Meaning | What to do | | --- | --- | --- | | Blocked | The receiving provider refused your mail, often due to a blocklist or policy | Check blocklists, links and authentication | | DMARC | Your domain failed DMARC alignment | Set up SPF, DKIM and DMARC on a domain you own | | Invalid Address | The mailbox doesn't exist | Remove the address. Don't resend | | Mailbox | The mailbox is disabled or unavailable | Remove or confirm the address with the contact | | Mailbox Full | The inbox is over quota | Retry later. Remove if it keeps failing | | Rate Limit | The provider is throttling how fast it accepts your mail | Slow down and spread sends out | | Recipient Error | The recipient's server had a problem | Usually temporary. Retry later | | Rejection | The server rejected the message for content or policy | Review content, links and list quality | | Sender Reputation | Your domain or IP reputation is too low | Send only to engaged contacts and warm up again |
Hard vs. soft bounces
- Hard bounces are permanent (invalid address, domain doesn't exist). Remove these contacts from your email lists.
- Soft bounces are temporary (mailbox full, rate limit). They may succeed later, but repeated soft bounces should be treated as hard bounces.