The bottom number doesn’t really mean much besides putting you at risk. What are her open rates? Click rates? If people click, what is the conversion rate? Etc
You can blast everyone on the planet but if it’s not targeted, personalized, etc it’ll be a waste of time and resources.
I’ve worked with some large e-commerce companies that aren’t that high, but >100M. They have very robust tracking, segmentation, personalization, etc. I couldn’t imagine anyone having success at that scale without those things at a 10/10.