SMTP only won for a relatively brief period. Nowadays it's mostly used for newsletters and transactional mails. Personal messaging moved to IM and Discord, busi

SMTP only won for a relatively brief period. Nowadays it's mostly used for newsletters and transactional mails. Personal messaging moved to IM and Discord, business messaging is now largely Teams/Slack. I sent someone a business email the other day. They told me I got lucky they even saw it, as they now communicate entirely via Slack. Slack isn't even trying to be an email competitor and it still wins. SMTP is still useful for cases where the additional feature-set of other platforms isn't important but a globally unique ID is.