Thank you for the reply. The problem is that parseaddr is designed to not fail IIUC, that’s why it may return empty strings. Client code has to check for these values instead of catching an exception—a mere style issue, weren’t it for the second bug. So I’m going to report that separately, and restrict the format in my project so that my code can just use string methods. I think I won’t open a feature request for a parameter to get exceptions, since parseaddr is designed not to.