> Do we live in a world of walled gardens, where the smaller mail servers would just have their mail be discarded, or something? Short answer: kinda yes. Long

> Do we live in a world of walled gardens, where the smaller mail servers would just have their mail be discarded, or something? Short answer: kinda yes. Longer answer: Especially if you launch something new (new Domain, only a few dozens subscribers/ transactional mails every day), it's difficult to build up enough reputation such that your mails gets into the customer's inbox - or even delivered at all. So even if email is included at your webhoster, you'll want to use a provider with whom you can be sure that your emails make it into the inbox.