I frequently get requests to create a mailing-list with 5 to 50 email addresses and for that, the Mailing List / Import feature where you have one email-address for each line is extremely helpful ... in theory.
In practice, however, in its current state, it doesn't work because people never send lists with just the pure email addresses, and always send them in the format Name <firstname.lastname@example.org>. The reason they do is obviously because that's how pretty much every mail client delivers email-addresses when you copy them out of a list.
So, for that feature to properly work, it should have a regular expression that gets the actual email-part from that format, or just the email-address. Also, it would be nice if blank spaces and blank lines are automatically discarded (also trivial to do when the emails are run through a regular expression).
It's quite tedious when, after manually removing 'Name <' and '>' from 10 or 15 addresses because I don't have a reg-exp processor available, it still doesn't work and I have to search for the blank space at the end of one of those lines, or there's one final linebreak.
One could argue that this is a feature-request ... but in its current state, to be honest, that import feels broken, so I think calling it a bug is fair.