[Bino]

It was unnecessary to split the protocol into two ports when STARTTLS came along shortly after. As for myself, I also thinks it's nice that you can partly identify the usage of a port by connecting to it.

https://en.wikipedia.org/wiki/SMTPS

[MichaelGG]

Still doesn't address sending credentials plaintext or what benefit this has, at all. Adds another roundtrip for no benefit. Using TLS doesn't change the identification, just requires a few packets to be exchanged; not a huge deal.

So again, how did Lavabit help its customers by not forcing TLS for IMAP?