This section summarizes the structure of an e-mail that is transmitted in HTML format.
HTML e-mails use HyperText Markup Language (HTML) tags to apply formatting to the content. For example, HTML can be used to apply different font sizes and styles to specific parts of the Message. E-mails that use the HTML format are often visually engaging and have improved readability when compared to plain text e-mails.
Typically, the improved readability of HTML e-mails means that they are used wherever possible, especially when the recipient is an operator or engineer. However, if you want alarm e-mails to be redirected to a Third Party application, you should determine whether the Third Party application supports HTML e-mail:
- If the Third Party application supports HTML e-mail, you can use HTML format e-mails for alarm redirections to the application.
- If the Third Party application does not support HTML e-mail, you will need to use Plain Text format e-mails (see Plain Text Format E-Mails).
You will also need to use Plain Text format e-mails if your e-mail application does not support HTML e-mails (many modern e-mail applications have HTML support as standard).
To set ClearSCADA to transmit e-mails in HTML format, you need to configure the User account of the recipient. In the User configuration, you need to specify that the User can receive e-mails in the HTML 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 HTML format for any e-mails that it sends to that user.
The Subject of a HyperText Markup Language (HTML) format e-mail can only contain characters from the 7-bit US-ASCII character set. This character set supports a limited range of symbols, and any characters that cannot be represented in HTML are replaced by a question mark symbol (?). For more information on this character set, see Plain Text Format E-Mails.
The Message of an HTML format e-mail is inserted between the e-mail’s <body> and </body> HTML tags automatically. It can contain characters from the UTF-8 character set or HTML tags and character entities. Any tags and character entities in the message need to conform to the HTML 4.0 Transitional standard, for example, they should:
- Use the <p> and </p> tags to start and end each paragraph
- Use the <br> line break tag to force content to start on a new line.
Do not include any reserved characters in the Message content—instead, specify the relevant character entities for such characters. For instance, specify the character entity < instead of a left angle bracket (<). The character entity is replaced by the corresponding character when the e-mail is rendered in the e-mail client.
If an HTML format e-mail is configured to include an Alarm View hyperlink:
- The hyperlink will only be included if an Alarm View exists for the item that is in alarm. For information on configuring Alarm Views, see Define an Alarm View in the ClearSCADA Guide to Core Configuration.
- The hyperlink will display the full path to the Alarm View item in the database.
You can send an alarm redirection e-mail to multiple recipients, some of whom might use e-mail clients that can receive HTML format e-mails, while others might only be able to receive plain text e-mails. HTML format e-mails are sent as multi-part e-mails: the first part contains a plain text version of the e-mail; the second part contains the HTML version of the e-mail.
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.
Further Information
Supported character entities: see http://www.w3.org/TR/html4/sgml/entities.html
Supported HTML tags: see http://www.w3.org/TR/1998/REC-html40-19980424/