Dear Support, I am experiencing an issue with my PEC mailbox configured in Thunderbird. In the sender column, an incorrect email address often appears, unrelated to the actual sender of the received email. In some cases, I see the phrase "on behalf of:" followed by an email address that has no connection to the message in question. This issue makes it difficult to correctly identify the real sender of emails. I have already checked my account configuration and updated Thunderbird to the latest version, but the problem persists. Could you please provide guidance on how to resolve this behavior? I am available to provide further details or screenshots of the issue if needed. Thank you in advance for your assistance.