SpamExperts can check whether a recipient exists before accepting mail for delivery. If a new mailbox receives a recipient error, verify the destination's view of that address as well as the filter's configuration.
01 Diagnose a valid address being rejected
- Confirm the mailbox or alias exists at the actual destination mail service.
- Check the exact recipient used by the sender, including spelling and domain.
- Review the domain's mailbox overview or configuration in SpamExperts. Inspect discovery and filtering settings for the address.
- Use the available destination or SMTP test to see how the destination responds to recipient verification.
- After creating the missing recipient or fixing the destination response, an authorised domain user can open Continuity > Clear Callout Cache - Incoming and select Clear. This refreshes that domain's cached recipient checks. Send a new test afterwards, or ask us to assist if the control is unavailable.
02 Check the destination
Recipient callouts can use an empty envelope sender. A destination that rejects these checks or blocks the filtering service may incorrectly make valid users appear unavailable. The receiving mail administrator should review the actual SMTP response.
Clearing this cache does not change message classification or correct a wrong destination. First fix the underlying recipient or route, then refresh a stale result when there is a specific reason.
Common questions
Should I enable catch-all to fix it?
Do not use catch-all as a routine workaround. It accepts addresses that may not exist and can increase unwanted traffic. Correct the specific mailbox or verification issue.
Why does an alias fail while the main address works?
The destination or filter may not yet recognise the alias. Check both systems and any cached recipient result.
Does creating a mailbox in the filter create its actual inbox?
No. Filtering configuration and mailbox provisioning are separate. Create the account at the service that stores the mail.
Give us the domain, recipient, destination hostname and complete rejection with a timestamp. A successful webmail login does not prove that the mail server accepts recipient-verification connections from the filtering service.