The Simple Mail Transfer Protocol (SMTP) is used to send emails. Initially, emails were sent without encryption.
Then, in order of privacy and data integrity, the cryptographic protocol SSL (Secure Sockets Layer) was intended by Netscape Communications Corporation.
Subsequently, due to many security issues, SSL was replaced by the much more reliable TLS (Transport Layer Security). With very few exceptions, all modern public mail servers use TLS.
However, the implementation of SSL/TLS requires a relatively large resource, which some of the embedded devices do not have.
This is the case with TCW122B-CM and TCW181B-CM. Both devices are based on an 8-bit chipset and do not have the resources to support SSL/TLS. However, they support SMTP and can be used to send emails as alarm notifications.
Before reviewing the possible solutions for email sending some forewords for the right network settings.
The right network settings are extremely important for proper operation.
IP address, subnet mask, and Gateway must follow the logic of your network.
For DNS and timeserver, we recommend those of Google’s – 126.96.36.199 (or 188.8.131.52) and time.google.com. Of course, other ones can be used, taking into account the response time.
To be able to send emails, devices must have Internet access. The limited resource of the devices does not allow the presence of built-in inspection tools. Internet access can be checked indirectly. Disconnect the device from the network and apply its network settings to a standard computer. If the computer has access to the Internet, it would mean that the device will too have.
After the above settings/checks are done, the device should be connected to the network and powered up.
Possible email sending solutions
1. Gmail service
The service allows devices and applications that do not support SSL to send e-mail messages.
This option uses a restricted Gmail SMTP Server. The restriction is that recipients can only be Gmail or Google Workspace users. The maximum number of messages sent depends on the account usage limit.
To set up your device to use this service, make the following settings:
More information about the service can be found on the Google support page.
2. SMTP2GO service
The main business of SMTP2GO is handling email delivery. They offer several paid plans, but they also have a free option if the emails sent per month do not exceed 1000.
The service is relatively easy to use. You must first create an account by sending an email and password. Keep in mind that emails on public domains are not supported, only emails on private domains can be used.
Once the account is created, log in and go to Settings->SMTP users. Click on Add SMTP User button and create an SMTP user by entering Username and Password.
The service can use the following settings for TCW122B-CM(TCW181B-CM):
Below is a screenshot from TCW122B-CM controller with SMTP2GO account setup.
More information about the service can be found on the SMTP2GO FAQ page.
3. TCW gateway service
This service is based on a Teracom server. The service is free, but there are restrictions on the number of emails sent during the day. It is recommended to use this service only as a last resort.
The recipient email here can be any valid email address.
Disclaimer: Teracom is not associated in any way with vendors of services mentioned here and is not responsible for their performance.