Issue
The EmailHandling library implements function blocks to send and receive emails with the controller application support secure and unsecure communication with an email server.
Since it is not recommended to use unsecure communication over public networks and above all over the internet.
Furthermore, the most popular public email servers do not support unsecure communication. Therefore, a direct communication between the M241/M251 controller and the public email server is not possible.
Resolution
To address this issue, the recommended third-party tool to use is stunnel.
Stunnel is a proxy designed to add TLS encryption functionality to existing clients (controllers) and servers (public email) without any changes in the program’s code.
Stunnel uses the OpenSSL library for cryptography, so it supports whatever cryptographic algorithms are compiled into the library.
Disclaimer
The views and opinions expressed in this article are those of the author(s) and do not necessarily reflect the official policy or position of Schneider Electric.
