If you would, please provide a line of your data (even though you've described it--and redacted, if necessary), and then show a finished line the way you want it.

Also, unless you absolutely know that there are no commas in the email addresses (commas are allowed in the local part of email addresses if enclosed by double-quotes), then you should use a csv parsing module, such as Text::CSV_XS, instead of splitting the line on commas.