Recently I had to send an email newsletter to many recipients. The email addresses supplied were in a single column of a spreadsheet. My mass email sending application uses a comma separated list of addresses. Not usually a problem, a simple CSV export of this list does the job. Only in this case some email addresses were not in a valid format.
For examaple:
foo@domain.com [foo@domain.com]
I needed a quick way to identify each of these non-valid addresses and manipulate them into a usable format.