A healthy email list is a responsive email list.
It is one thing to have an email list and another to have a responsive email list. The difference between the two however is that a responsive email list is one that brings in the needed results.
For example, if you have 10.000 email addresses on your list and having sent out a newsletter informing your subscribers of a promo, about 6.000 subscribers responded by either buying the product or even asking questions, then your list is responsive.
Email list is an important tool for marketing and must be treated as a valuable investment. Annoying subscribers with spam and unsolicited messages is one sure way to make your email list non-responsive, as users gradually becomes uninterested in opening your new messages.
The best way to build a healthy list is to make sure you’re always asking permission before adding someone to your list.