Enable receiving and reply emails

Thank you all for your valuable suggestions and support! @pfaffman , @Jagster , @Canapin , and @denvergeeks — I appreciate your help. I wanted to update you that it’s working now! I removed all my old configurations, upgraded Docker to the latest version, and ensured the required MX record was correctly added. Telnet still doesn’t work, but I can now successfully receive replies. Thanks again for guiding me through this!