other: Question lost connection after BDAT / DATA in postfix about docker-mailserver HOT 3 OPEN

Please note that this response was created using generative AI, leveraging previously available information from the repository. This information may be helpful. However, it is our strong recommendation that you carefully consider the information before blindly applying it.

It seems like you've already conducted a thorough investigation into the issue with large emails being dropped when interacting with Microsoft servers. Given the specific nature of the problem (connection loss at exactly 64KB), this might suggest an issue related to network or protocol handling specific to how Microsoft's servers interact with your mail server configuration.

Here are a few additional steps you might consider to further diagnose or mitigate the issue:

1. Network Trace: If not already done, perform a network trace (using tools like Wireshark) to capture the traffic between your server and the Microsoft servers. Look specifically for any resets or unusual sequence of packets around the 64KB mark.

2. Contact Microsoft Support: Since the issue is predominantly with Microsoft servers, reaching out to Microsoft technical support might provide insights or known issues related to BDAT/DATA commands with their outbound protection services.

3. Test with a Simplified Setup: Temporarily configure a test environment with a minimal setup (bypassing HAProxy and any other intermediate network services) to see if the issue persists when connecting directly to the internet.

4. Review SMTP Conversation: Check the SMTP conversation logs in detail to see if there are any clues in the responses from Microsoft servers just before the connection drops.

5. Adjust Timeout Settings: Although it seems unrelated, adjusting the timeout settings for your SMTP connections might help if the issue is due to delayed responses from Microsoft servers.

6. Consult Docker-mailserver Community: Since this is a complex issue, consider posting a detailed question in the Docker-mailserver community discussions or forums. Other users might have faced similar issues or could offer new suggestions based on their experiences.

Given the complexity of the issue and the steps you've already taken, it might also be beneficial to consult with a network specialist who can offer a deeper analysis of the network traffic and potentially identify any anomalies that are not immediately obvious.

This comment was generated by Glime.

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