Sending mail to people who didn’t ask for it is often just asking for trouble. Having people give you permission to send to them is much better.

In an ideal world you want first-party consent meaning that people directly subscribed to your list. You have measures in place to confirm that they really did sign up and someone didn’t just stuff their address into a subscription form. These people want your emails.

In a slightly less ideal world you have second-party consent. This means that another organization shared their list of first party consented subscribers with you by prior arrangement. Provided that the arrangement was clearly communicated to the subscribers at the point of acquisition then this is mostly fine. These people probably have an interest in your emails and are likely expecting to hear from you.

In a not so ideal world you are working with third-party consent. This means that first party consent was obtained at some point somewhere sometime for something broadly related to why you now want to reach them. This is the consent level you hope for if you use a data broker and not just scraped or stolen data. These contacts don’t know you. There is no relationship. It’s a stretch to say they really consented. They clicked a box at some point in their lives and now they ended up on your list. Treat these strangers with the utmost care and respect. Your first mail to them should be an introduction not a pitch; tell them how they ended up on your list and how to get off it. Success here means earning trust, not jumping in with a special offer.

While permission is often a sliding scale of likely success with first-party consent being the most optimal, it doesn’t have to be. At scale there are strategies where programs that use third-party consent can be successful without a blast radius of bounces and complaints.

Of course there is also the chance that you are operating with zero consent to contact people. Outside of spamming there are some legitimate scenarios for doing this but that deserves a separate article.