I have an email body. It contains several lines of text. I need to extract the first occurrence of a string that:
You can use a lazy quantifier with
(?:Specific\ text\ after\ which\ I\ need\ to\ search:) [\s\S]+?\K (\b\w+-\w+-\w+-\w+\b)
\b is a word boundary,
\K deletes everything to the left from the match.
See a demo on regex101.com.