I'm confused as to what you mean. Are you asking whether emailing a popular youtuber is worth the effort? Most popular youtubers wouldn't have the time, I don't think, to answer all the emails they get from fans.
Yeah big YouTubers don't have time to do all that BS...only time I'd see them promote anyone is a real good IRL friend, and not even a shout-out like include them in their video or something is what they would do. Or collaborate with them..and that's only in real life best friends lol
It depends on the purpose of the mail, and how big the channel is. I've managed to contact relatively big channels, between 50-100 thousand subscribers, but never higher than that. Although it is worth the try, if it's something that you think will interest them
the only people that email me are networks lol.
there's no harm In trying, I know a few that read their mail, but if their subs are in the millions it's probably not worth it as they likely get spammed a ton