First things first, there will always be emails going to spam, no matter if you’re sending a one-to-one email personally or using an ESP to send bulk emails. Even the biggest and most reputable ESPs have emails landing in spam, guaranteed.
Also, an email message lands on your spam folder doesn't mean it also lands on your subscribers' spam folder.
Mailbox providers (Gmail, Yahoo, Hotmail, etc.) use thousands of signals to determine where to place your email message (spam, promotions tab, or primary inbox).
One of the signals is your subscriber's history engagement (if they have previously opened / clicked / replied to your email). The more engagement, the better.
So for you, it might land in the spam folder. For John, it may land in his promotions tab. For Lisa, it could be in her primary inbox.
If you do email marketing correctly, most emails (99%) won’t go to spam.
Here are some best practices to reduce emails going to spam: