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Body delimiters use Regular expressions to match and remove Body content from the email. This allows you to remove the content that you deem irrelevant and leave the relevant content in the email body which will be shown in the Issue description/comment. The expressions can be as simple as matching one word from the start of a line or they can be more complicated for example matching multiple words and numbers. Body Delimiters are set within Profile > Project Mapping > Pre-Processing.
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Using Body Delimiter with styled text
If your Profile is using converting HTML to Wiki Markup for Jira to render the emails then the expression will become more complicated. Wiki markup adds extra characters to the email body so that when Jira renders the email is getting rendered content it will display the text using the style that is defined by the Wiki Markup. This makes the regex more complicated to make as the expression will need to also match these characters if the word/phrase uses Wiki markup to change the appearance. To check if you are using Wiki markup go to Profile > Email > HTML and inhere there is are some settings that enable you to select which styles you would like to render. For example bold Bold and italicItalic.
Difference between rendered and non rendered text content
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