Thanks for your thorough reply. Yes, SMTP was designed when "everybody knew everybody" on the Interne. My major doubt is why, in the age of DKIM, SPF et al thes

Thanks for your thorough reply. Yes, SMTP was designed when "everybody knew everybody" on the Interne. My major doubt is why, in the age of DKIM, SPF et al these practices are allowed. I just found out this is the easiest way to resend a message if you have a very primitive MUA, so maybe that's the reason? I doubt Google will answer me this question :)