465 is considered obsolete in the sysadmin community but yes of course various providers still use it as certain providers have to be dragged across the floor to update their systems, broadband providers are particularly guilty of this problem.
e.g. plusnet not so long ago still didnt even support encryption, I dont know if its still the case now, but this is what happens when someone provides email as a free addon rather than a core part of their services.
Many modern email clients have completely dropped support for 465 implicit ssl.
So my suggestion still stands, 25, 587 plain and starttls, and 465 implicit ssl for those (legacy) providers that have not updated their systems to modern standards.
I personally dont use plain ever on email, but I suggested to keep plain for 25 and 587 as there is probably providers out there that dont support starttls.
As far as I can see starttls is already functioning properly in 6.0.8 and 6.0.9 so I dont think there is anything for eric to fix there, it wont work if the provider doesnt support it.