This section summarizes the structure and limitations that apply to an e-mail that is transmitted in Plain Text format.
Plain Text format e-mails have very little formatting - they only contain alpha-numeric characters, punctuation, tabs and spacing. While this means that they may be less visually appealing when viewed via an e-mail client, the lack of formatting makes them more appropriate for use with other types of external application.
Typically, you only need to set ClearSCADA to transmit e-mails in Plain Text format if you need alarms to be redirected in e-mails to Third-Party applications. For example, the Plain Text format is often required when redirecting alarm e-mails to Third-Party telephony software.However, if the Third-Party application supports HTML e-mail, you may prefer to use the HTML format.
To set ClearSCADA to transmit e-mails in Plain Text format, you need to configure the User account of the recipient (which may be a system user or a Third Party application). In the User configuration, you need to specify that the User can only receive e-mails in the Plain Text format (see Define the E-Mail, Pager, and Voicemail Contact Settings for a User in the ClearSCADA Guide to Security). When this is in place, ClearSCADA will use the Plain Text format for any e-mails that it sends to that user.
The Subject and Message of a Plain Text e-mail can contain characters from the 7-bit US-ASCII character set. This character set was developed to support the American English language and so only supports a limited range of other characters—for example, the accented characters and ligatures (joined characters) used in many European languages are not supported. HTML coding, if present, will be removed, but some tags, such as < are converted to their textual equivalent (for example, >). Any characters that cannot be represented are replaced by a question mark symbol (?).
If the 7-bit US-ASCII character set proves too limiting for the language used by the users on your system, we recommend that your system is configured to send only HTML Format E-Mails. HTML format e-mails are sent as multi-part e-mails, allowing the recipient to receive the e-mail in either HTML format, or plain text format, depending on the format supported by their e-mail client. The plain text version of an HTML format e-mail is sent using the less restrictive UTF-8 character set, which supports characters that are not supported by the more limiting 7-bit US-ASCII character set. (Many of the characters in alphabets such as Bulgarian and Russian, cannot be represented by the 7-bit US-ASCII character set.)
For an example that demonstrates how an e-mail’s layout differs when sent to users that can receive e-mails in HTML or plain text format, see Send an E-Mail in Different Formats to Different Users.