The IMAP connection test fails with an SSL routines::wrong version number error when trying to connect to a Microsoft Exchange Server. Sending emails via SMTP works flawlessly.
I have verified the connection and the SSL/TLS certificate from inside the Freescout Docker container using openssl s_client. The OpenSSL test is completely successful, confirms the certificate is valid, and completes the TLS handshake without any issues. Furthermore, the Exchange IMAP service works perfectly with other third-party applications. The issue seems maybe isolated to how PHP's stream_socket_client handles the TLS/STARTTLS negotiation with Exchange in this specific Docker environment.
Steps to reproduce:
Docker image (Version 2.1.0) on a Debian 13 host.
Navigate to a mailbox's Connection Settings -> Incoming Emails (IMAP).
Enter the details for an MS Exchange server.
Set the Port to 143 and Encryption to TLS (+StartTLS) (Note: The Exchange server is explicitly configured to handle TLS on port 143).
Enter valid credentials and click "Check Connection" ("Verbindung prüfen").
The UI throws a popup with a connection failure and an OpenSSL error code 1.
Note: Changing the encryption to regular TLS/SSL or testing Port 143 results in the same behavior. Disabling authentication throws a different error, but that is not the intended setup.
Here is the error without TLS:
Relevant logs and/or screenshots:
Freescout UI Error:
connection failed - stream_socket_client(): SSL operation failed with code 1. OpenSSL Error messages: error:0A00010B:SSL routines::wrong version number
Here is a screenshot of my actual problem:
Proof of successful connection from INSIDE the Freescout container:
Executing this directly inside the container returns a successful handshake:
openssl s_client -connect <exchange-ip-or-name>:143 -starttls imap -showcerts
Output snippet:
CONNECTED(00000003)
...
SSL handshake has read 3568 bytes and written 1717 bytes
Verification: OK
---
New, TLSv1.2, Cipher is ECDHE-RSA-AES256-GCM-SHA384
Protocol: TLSv1.2
...
Verify return code: 0 (ok)
Extended master secret: yes
---
. OK CAPABILITY completed.
Environment
Image version / tag: 2.1.0
Debian 13 - Docker
Possible Problems:
Strict hostname vs. IP validation in PHP (even when "Validate Certificate" is toggled off in the UI).
The Exchange certificate is issued strictly to the hostname and does not contain the internal IP address.
I'm happy to provide further logs or configs if needed – just let me know.
The IMAP connection test fails with an SSL routines::wrong version number error when trying to connect to a Microsoft Exchange Server. Sending emails via SMTP works flawlessly.
I have verified the connection and the SSL/TLS certificate from inside the Freescout Docker container using openssl s_client. The OpenSSL test is completely successful, confirms the certificate is valid, and completes the TLS handshake without any issues. Furthermore, the Exchange IMAP service works perfectly with other third-party applications. The issue seems maybe isolated to how PHP's stream_socket_client handles the TLS/STARTTLS negotiation with Exchange in this specific Docker environment.
Steps to reproduce:
Docker image (Version 2.1.0) on a Debian 13 host.
Navigate to a mailbox's Connection Settings -> Incoming Emails (IMAP).
Enter the details for an MS Exchange server.
Set the Port to 143 and Encryption to TLS (+StartTLS) (Note: The Exchange server is explicitly configured to handle TLS on port 143).
Enter valid credentials and click "Check Connection" ("Verbindung prüfen").
The UI throws a popup with a connection failure and an OpenSSL error code 1.
Note: Changing the encryption to regular TLS/SSL or testing Port 143 results in the same behavior. Disabling authentication throws a different error, but that is not the intended setup.
Here is the error without TLS:
Relevant logs and/or screenshots:
Freescout UI Error:
connection failed - stream_socket_client(): SSL operation failed with code 1. OpenSSL Error messages: error:0A00010B:SSL routines::wrong version number
Here is a screenshot of my actual problem:
Proof of successful connection from INSIDE the Freescout container:
Environment
Image version / tag: 2.1.0
Debian 13 - Docker
Possible Problems:
Strict hostname vs. IP validation in PHP (even when "Validate Certificate" is toggled off in the UI).
The Exchange certificate is issued strictly to the hostname and does not contain the internal IP address.
I'm happy to provide further logs or configs if needed – just let me know.