>, I wonder what has made SMTP such a stable protocol that has stood the test of time and what is the real reason we don't use XMPP There are probably multiple

>, I wonder what has made SMTP such a stable protocol that has stood the test of time and what is the real reason we don't use XMPP There are probably multiple reasons and we can't replay history to know which reason contributes the most but one key difference is that email accounts (SMTP) were pushed onto the regular non-techie consumers whereas XMPP was more of a geek tool that users had to pull and opt into. E.g. New students at a university automatically got a ".edu" email address. Residents got a free email account (ISP) with their cable service. Employees got a corporate email address. In other words, millions effortlessly got the utility of email/SMTP even without installing AOL CDROMS. To further reinforce email/STMP, if consumers want to order something from Amazon, they needed an email address to create an account instead of an XMPP address. Other forms of communication like XMPP/IRC don't have that widely disseminated self-reinforcing utility cycle so they stay a niche tool. What critical service in normal life requires an XMPP address? I can't think of any.