You could use regex to accomplish this. Unless we have more information about the pattern it will be hard to give you an exact match for your use case, but I have made a simple case using “sender” and matching the word directly after
The Matches activity returns all matches found. Are you looking for 1 or many matches? If just 1, use the Match activity. If you’re looking for many, can you describe the use case for getting multiple matches from one regex?