I use PSPAD as my default text editor. It’s been my favourite such application for years because it can do so much. Recently I was handed a CSV that contained email addresses for 25,000 users. I needed to pull out just the SMTP suffixes for some manipulation. PSPAD can do global search and replace with a REGEX and it seemed like just what I needed. The only challenge was to figure out what pattern matches everything in an email address up to and including the @ sign. Here’s the pattern I used.
That says to start at the beginning of the line, match any number of alphanumeric characters up to, and including the @. Easy.