One of the worst outcomes for you as an email sender is when your emails are reported as spam. Spam complaints are detrimental to your sender reputation, email deliverability in general, and can even lead to you getting blocked by ISPs. To stay safe, it's important to keep your spam report rate low.
Problem 1: You are targeting the wrong people
Trying to grow your subscriber base as big as possible, you might neglect to pick only those leads who fit your buyer persona and ideal customer profile (ICP). As a result, you'll collect a list that might include people who don't really want to hear from you. For them, your messages will be nothing but spam.