Bounce types
Hard bounce
A permanent delivery failure. The email address does not exist, the domain is invalid, or the recipient server has permanently rejected the message. Hard-bounced addresses should be removed from your list immediately.
Soft bounce
A temporary delivery failure. The recipient’s inbox is full, the server is temporarily unavailable, or the message is too large. Soft bounces are retried automatically.
Common bounce codes
| Code | Type | Meaning | Action |
|---|---|---|---|
| 550 | Hard | Mailbox does not exist | Remove from list |
| 551 | Hard | User not local / relay denied | Remove from list |
| 552 | Soft | Mailbox full / storage exceeded | Retry later; remove if persistent |
| 553 | Hard | Invalid mailbox name or syntax | Remove from list |
| 421 | Soft | Service temporarily unavailable | Automatic retry |
| 450 | Soft | Mailbox busy or temporarily blocked | Automatic retry |
| 550-5.7.1 | Hard | Message rejected by policy | Check content and authentication |
| 550-5.7.26 | Hard | SPF/DKIM authentication failure | Fix DNS records |
Bounce suspension
The HoopAI platform monitors your bounce rate continuously. If your bounce rate exceeds platform thresholds, email sending may be temporarily suspended to protect your sender reputation and the platform’s shared infrastructure.What triggers a suspension
- Hard bounce rate exceeding 5% over a rolling period
- Spam complaint rate exceeding 0.08%
- Sudden spike in bounces from a single campaign
How to avoid suspension
Verify your list before sending
Use the platform’s email verification tool or a third-party service to validate addresses before importing. Remove invalid and risky addresses.
Never use purchased lists
Purchased or scraped email lists have extremely high bounce rates and will trigger an immediate suspension.
Remove hard bounces promptly
After every campaign, review the bounce report and remove all hard-bounced contacts from future sends.
Resolving a suspension
If your account is suspended for excessive bounces:- Pause all outgoing email campaigns
- Export and clean your contact list — remove all hard bounces, invalid addresses, and unengaged contacts
- Document the steps you have taken to clean your list
- Contact support with your cleaning report to request reactivation
Cleaning your email list
When to clean
- Before importing any new list
- Before sending to a list that has not been emailed in 60+ days
- After any campaign with a bounce rate above 3%
- Quarterly for actively used lists
How to clean
Use email verification
Use email verification
Run your contact list through the platform’s built-in email verification or a third-party verification service (ZeroBounce, NeverBounce, BriteVerify). These tools check whether each address is valid before you send.
Remove role-based addresses
Remove role-based addresses
Addresses like info@, sales@, admin@, and support@ are role-based and often have higher bounce and complaint rates. Remove them from marketing lists.
Segment by engagement
Segment by engagement
Create a smart list of contacts who have not opened or clicked any email in the past 90 days. Send a re-engagement campaign. If they still do not engage, suppress them.
Remove duplicates and malformed addresses
Remove duplicates and malformed addresses
Use the platform’s duplicate management tools to merge or remove duplicate contacts. Fix obvious typos (
gmial.com to gmail.com).Re-engagement campaigns
Before removing inactive contacts permanently, try a re-engagement campaign:- Create a smart list: contacts who received at least 5 emails in the past 90 days but opened 0
- Send a short, clear email asking if they want to stay on your list
- Include a clear CTA that confirms interest
- Wait 7-14 days
- Contacts who do not engage should be suppressed from future marketing sends
Bounce rate benchmarks
| Metric | Healthy | Concerning | Critical |
|---|---|---|---|
| Hard bounce rate | Below 1% | 1-3% | Above 5% |
| Soft bounce rate | Below 2% | 2-5% | Above 5% |
| Overall bounce rate | Below 3% | 3-5% | Above 5% |
| Spam complaint rate | Below 0.05% | 0.05-0.08% | Above 0.08% |
Automatic bounce handling
The HoopAI platform handles bounces automatically:- Hard bounces — the contact’s email is flagged and they are excluded from future email sends
- Soft bounces — the platform retries delivery. After multiple consecutive soft bounces, the contact is treated as a hard bounce
- Bounce logging — all bounce events are recorded in the contact’s activity timeline
- Campaign statistics — bounce counts and rates are displayed in the campaign statistics dashboard
Frequently asked questions
Can I re-send to a hard-bounced contact?
Can I re-send to a hard-bounced contact?
No. Once a contact’s email is flagged as a hard bounce, the platform blocks further email sends. If you believe the bounce was incorrect, you can manually remove the bounce flag, but proceed with caution.
Does the bounce rate include soft bounces?
Does the bounce rate include soft bounces?
Suspension thresholds are based primarily on hard bounce rates. Soft bounces are tracked separately.
How quickly are bounces reported?
How quickly are bounces reported?
Hard bounces appear within minutes. Soft bounces may take longer as the platform retries delivery.