To be clear: I specifically chose the feedback forum, not one of support forums, because this was meant as a feedback topic, not a “I am looking for help/instructions for my site(s)” topic.
To make the point again in more detail: Defaulting to simple PHP mails has been the industry standard for php web apps for like 20+ years and Invision Community is no exception to this. It (usually) works right out of the box without the need for any configuration.
There is now a significant change happening in this area. It’s something that is all over the web tech news and I see it happen across my various websites as well. Mailbox providers are significantly raising the bar to get mails delivered, demanding multiple positive checks for the various authentication options. This makes it a concern for many (self-hosted) IPS customers who start out new or usually don’t touch the default settings. They will wonder why so many registrations get stuck or why mails don’t seem to get delivered at all, because Google throttled the delivery after a php bulk mail without proper authentication. Right now, the IPS description calls the option “sufficient for most sites”, but this might be worth reconsidering. And that was the point of this topic. I’m not making a claim about how this could be addressed. Maybe it can be reliably addressed directly in the code, maybe not. Maybe the onboarding process should instantly ask for SMTP details. Maybe it can be helped indirectly with things like allowing different services for transactional and bulk mails. All I tried was raising awareness for this issue, because I see it happening all the time and I see it getting worse.