Yeah, but unfortunately companies are also really, really, really good at putting you on mailing lists/ADLs that you never, ever would have signed up for on your own.
I went to a coffee shop in Palo Alto, bought a coffee, paid by Square, found I was now on one of their Square Marketing ADLs. Never asked for it, never would have asked for it, would have said "Hell no" if I were asked. Flagged it as Spam. Seriously considering never visiting that coffee shop again, but have at the very least switched to paying by cash...
Seriously, cut the bullshit. I don't want to be signed up to your list just because I bought something. Ask me if you want me on your list - if it's something I care enough about, I'd actually be okay with it.
1. Start out with an email transaction that follows up purchases done in the MVP to registered users. All that receive the emails have accounts since the MVP required it. It's not hard to setup automatic emails through code... It's hard to think of edge cases though.
2. Change in spec: more people buy if we change the UX and cut the registration.
3. Send an email to the customer. Oops - no account to unregister.
4. (This is the step that was missing) Change the code that handles emails so everyone can unsubscribe.
Sometimes it's important to get something out quick and things aren't always dark UI / UX on purpose. Users are often blaming us devs for our dark evil powers when all we did was shake out some code on a too tight deadline.
Yeah, sure, nevermind that there is a new list you have to unsubscribe for every month.
I never do a second buy, sometimes I have the energy to do a 1 star review for anyone that sends me mails that I couldn't avoid during the purchase.
I have gotten lazy about looking for unsubscribe links and more aggressive about hitting"report spam" on Gmail