Overview

You may experience an issue with the Kerio Connect server where emails fetched via POP3 marked with BCC (Blind Carbon Copy) are not being processed and delivered correctly. This problem affects all users in the domain. The emails are downloaded through a catch-all account but are not delivered to any of the BCC recipients. 

Solution

The issue with BCC marked emails not being processed by the Kerio server can be resolved by making the following changes in the Kerio Connect server settings:

1. Disable the Insert X-Envelope-To header to locally delivered messages option. This can be found under Configuration > Advanced options > Miscellaneous tab.
   
   
   • More details about this feature can be found in our X-Envelope-To Header Is Showing All BCC Recipients article
2. Optionally, disable the Drop duplicate messages option in the POP3 config
   
   
   • This particular option is necessary to ensure that Gmail emails are delivered to BCC recipients. Gmail, as opposed to other providers (for example Outloook), will create and send individual copies of the same email to the catch-all mailbox, and this option will lead to the "duplicates" to not be processed.

Summary

By adjusting the settings in the Kerio Connect server, users can resolve the issue of BCC emails not being processed and delivered correctly. This involves disabling the "Insert X-Envelope-To header to locally delivered messages" and "Drop duplicate messages" options in the server settings.

FAQ

1. What is the "X-Envelope-To" header in an email?
   The "X-Envelope-To" header is a part of the email that contains the recipient's address. If this is not correctly populated, it can lead to issues with email delivery.
2. What does the "Drop duplicate messages" option do?
   This option, when enabled, prevents the delivery of duplicate emails. However, in this case, disabling it ensures that Gmail emails are delivered to BCC recipients.
3. What is a catch-all account?
   A catch-all account is an email account that is set up to receive all emails that are sent to an incorrect email address within a domain.