Duplicate messages between kopano accounts
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Some of the users in our system regularly receive duplicate messages in their inboxes. They receive duplicates for both calendar events (an organizer creating, updating or canceling an event), and regular mail. In tracing the messages through our system, we’ve noticed that they originate with the sender. Our MTA receives duplicate connections from kopano – same IP address but different port numbers. The duplication happens with the generation of two messages being created/sent from the original sender. In other words, a kopano user only receives duplicates when a message is sent from a kopano account. We have not yet had any reports of the duplication occurring when a user receives a message from an external account.
This issue seems to affect some users and others not at all. At first we wondered if the issue is related to the affected users using z-push. But not all of the affected senders have z-push devices setup. So far all of the senders who have generated duplicates are using MacOS. However, not every MacOS user generates duplicates. So there is something else that is creating the duplicates. It has been difficult to identify and reproduce.
This post is an update and expansion of the issue reported here.
What can I provide in terms of logs or additional information to better document this issue? Has anyone else experienced this?
Our System:
- Kopano Core 11.0.2
- PHP 7.3.33
- Zend Engine v3.3.33
- Nginx version 1.21.4
- Kopano Webapp v5.2.0
- Debian 10 Buster
- Z-push 2.6.4
