I had a look a the Net::SMTP source, and it would appear that it does not parse out the termination string from whatever you pass in. I mean, it doesn't look as if that's something it's even trying to do.

If it's supposed to and it's not - is this a bug? (ie: *should* it?)

If I were using it, I think it'd be nice if it did do that, but I'm not sure I'd call it a bug. Either way, I think its actual behavior should be documented.