The NBS is a pretty interesting idea. I don't think we ever tried that.
As for filling it out, I default to the type of stuff I mentioned in the article, like "Open this email to read the details" or some such. It's not really a big deal if it gets cut off, but if it does show up it drives action. I'd opt for something like that over a slogan unless you're in heavy brand-building mode and want to increase familiarity with your subscribers. I think it's a great conversation to have with the team at any rate.
Awesome! I think you can basically just write them the way you're used to and then add another sentence on the end. I'm happy to hear your team actually has a standard in the first place. A/B testing longer ones might not reveal much difference since many people will see the same thing. You may just catch some few that could see a little more.
Please let us know what the team says.
That all makes good sense. It also sounds like it won't work very well... Wonder how many folks will try this and then get upset if they keep getting email, leading to a SPAM flag? Hopefully it works as intended but this would be pretty hard to test ahead of time.
Yeah, as Austin said. Interestingly, though, mine didn't have a subject line at all. I'm not sure why that would be the case. As this is still Beta software, I wouldn't sweat the details TOO much yet as they're likely to change. The weird 'to' address is what I didn't understand, but I'm sure some folks around here would be able to parse that somehow.