Email

The following template formats are available for the Email publisher

• Plain Text: Used if "Receive email in HTML format" is unticked in the recipient's User Preferences.
• HTML:  Used if "Receive email in HTML format" is ticked in the recipient's User Preferences. Ensure that you use simple HTML tags and attributes that work across all email clients

HipChat

The following template formats are available for the HipChat publisher

• Text: Used if "Message Format" is set to "Text" in the recipient's User Preferences or it is set to "Default" and the "HTML message format by default" option is unticked for the publisher. 
• HTML: Used if "Message Format" is set to "HTML" in the recipient's User Preferences or it is set to "Default" and the "HTML message format by default" option is ticked for the publisher. Used if "HTML message format" is selected for the publisher of subscription. The allowed HTML tags are: a, b, i, strong, em, br, img, pre, code, lists, tables
• Card: This is a rich message format specified as JSON. Used if "Send as card" is ticked for the publisher. An alternate text or HTML format will also be sent, depending on the message format options, for use with HipChat clients which do not support Cards.
  
  

Refer to HipChat Messages for more details on these formats.

Private Message

The private message publisher only supports a Text template format.

Slack

• Text: Always used
• Attachments: Used along with the Text format if "Include attachments" is ticked for the publisher

Stride

• Text
• Markdown
• Panel
• Card 

Teams

• Text
• MessageCard

XMPP

The XMPP message publisher only supports a Text template format.