(sorry if I insisted. A lot of people still believe 465 is deprecated. I wanted to correct that) For preference, the RFC also mentions implicit SSL is the goal

(sorry if I insisted. A lot of people still believe 465 is deprecated. I wanted to correct that) For preference, the RFC also mentions implicit SSL is the goal. Given how far it has come, with 465 now being resurrected, I will not be surprised when in the future STARTTLS becomes deprecated - and maybe other ports besides 465. All it takes is a few large email providers to stop accepting port 587 ... and 25. Just look at how everybody has jumped into using DKIM and MTA-STS which are way more complicated and ugly, but almost required if you want your email delivered.