A bounce is an email sent to an alias that the destination server could not deliver. AliasFleet records bounces in Analytics, in the Deliverability & Bounces tab, which shows total bounces, bounce rate, and classifications, with a ledger of each failed delivery and its diagnostic. Soft bounces retry automatically. Hard bounces need a fix to the alias or the destination.
The Deliverability & Bounces tab is part of Advanced Analytics. A plan without Advanced Analytics shows an upgrade card in place of the ledger. On the per-alias Analytics page, MTA bounce rejection logs are listed as a Business plan feature.
How do I open the Bounces tab?#
- Open Analytics in the dashboard sidebar.
- Select the Deliverability & Bounces tab.
- Read the three summary cards at the top: Total Bounces, Bounce Rate, and Classifications.
- Scroll to the Delivery Failures & Bounce Ledger below the cards to see each failed delivery.
What do the three bounce stats mean?#
Total Bounces counts rejected SMTP deliveries in the selected period.
Bounce Rate is bounces as a percentage of mail received in the selected period. The app labels a rate of 5% or below as Optimal range and a rate above 5% as Elevated threshold.
Classifications counts the distinct reject categories in the selected period.
What are the bounce classifications?#
| Classification | Meaning | Action |
|---|---|---|
| Soft (temporary) | The destination server deferred delivery, for example because of rate limiting or a connection timeout. | None. Automatic retries run. |
| Hard (permanent) | The destination server permanently rejected the message, for example because the recipient address does not exist. | Verify the recipient address or update the forwarding destination. |
| Spam / Policy Blocked | The destination server blocked the message under a spam, blacklist, or DMARC policy. | Check sender reputation and custom domain DNS authentication. |
What does each bounce reason mean?#
Each failed delivery in the ledger carries one diagnostic, with a title, an explanation, and an action. The diagnostics the app recognises are:
| Diagnostic shown | What causes it | What to do |
|---|---|---|
| Temporary Rate-Limit Deferral (421) | The destination provider is temporarily busy or throttling inbound delivery. | No action. Automatic retries are running. |
| Temporary Connection Timeout | The destination mail server did not connect in time or suspended the connection queue. | No action. Automatic retries are running. |
| Invalid Recipient Mailbox (550) | The recipient address does not exist, has a typo, or was deactivated by the provider. | Verify the recipient address or update the forwarding destination. |
| Security / DMARC Policy Block | The destination server blocked the message for content reputation or upstream DMARC policy. | Check upstream sender reputation and custom domain DNS authentication. |
| Permanent Delivery Rejection | The recipient mail server permanently rejected the message. | Verify that the recipient or destination address is active. |
| Temporary Delivery Deferral | The mail system met a temporary delay transferring the message. | No action. Automatic retries are running. |
Alias level causes also produce bounces:
- Deactivated alias. Mail sent to a deactivated alias is rejected and bounces back to the sender. Reactivating the alias resumes forwarding.
- Deleted or purged alias. Mail sent to a purged alias bounces permanently and cannot be recovered. A purged alias address cannot be used again.
- Address that does not exist. Mail to an address that is not an alias on the account is rejected as an invalid recipient. Check the spelling or create the alias.
What bounce text does the ledger show?#
Each ledger entry shows the recipient address, the alias it arrived through, a badge for the classification, the date and time, and the diagnostic title, explanation, and action. The diagnostic text comes from the destination server reply, cleaned to a code and wording, for example a 550 reply with "user unknown" wording. When no diagnostic is recorded, the ledger shows "Server delivery timeout / rate limit reached" and labels the entry Temporary Delivery Deferral. The fallback text "The destination mailbox provider rejected this email (550 User Unknown)." appears in the email detail view when a bounce there has no diagnostic.
The ledger filters by classification (soft, hard, or spam), by alias, or by searching for a recipient address or error text.
How is a bounce different from a blocked email?#
A blocked email is stopped by AliasFleet before forwarding begins, because the sender sits on the blacklist. It never reaches the destination inbox, the spam folder, or any other folder. A bounce is a delivery failure for mail already sent onward, for example mail to a deactivated alias or a destination the provider rejects. A block happens before forwarding; a bounce happens during or after forwarding. Blocked attempts appear in the blocked counts; failed deliveries appear in the bounce ledger. For the full explanation of blocked mail, see Blocked Emails Explained.
How do I investigate a high bounce rate?#
- Open the Bounces tab and read the bounce rate and the classifications count.
- Filter the ledger by classification to separate temporary failures from permanent ones.
- Open a bounce entry and read its diagnostic title, explanation, and action.
- Check the affected alias in Alias Performance for its forwarded and blocked counts in the same period.
- Fix the cause: reactivate a deactivated alias, correct or re-verify the destination address, or remove a sender rule that rejects wanted mail. See Using Sender Rules.
- Check again after the next delivery window. Soft bounces clear on retry without action; hard bounces stay until the cause is fixed.
How do I turn on bounce notifications?#
In Settings, the Delivery Notifications option covers email delivery failures and bounces. Open Settings, find Delivery Notifications, and enable it to receive alerts when deliveries fail.
Troubleshooting#
- Bounce rate above 5%. The app labels this elevated. Check the ledger for hard bounces first, since soft bounces retry on their own.
- All bounces sit on one alias. Check whether the alias is deactivated or its destination is unverified. Alias Performance shows the alias in the context of the whole account.
- A bounce has no diagnostic. The ledger shows "Server delivery timeout / rate limit reached" with a Temporary Delivery Deferral diagnostic. Verify that the destination address is active and spelled correctly.
- Expected mail is missing and no bounce appears. Check sender rules and the blacklist. Blocked mail stops before forwarding, so it never reaches the bounce ledger. See Blocked Emails Explained.
- No bounces are shown. The ledger shows "No recent delivery failures" when the selected period has none.