Proton Mail "Protocol Error"

Proton Mail "Protocol Error", Any clues what could this mean?

batshades Master Posts: 66 Points: 117 Rating: 16 Authority: 17 Joined: 17 October 2009	#1 0 09 January 2023 03:00:42 I have set up everything as Proton has instructed but when Authenticating Imap, "Protocol error" is returned as the result. I don't know enough about this to know what to try next. Thanks in advance for any assistance.

Miloš Radovanović Guru Posts: 293 Points: 526 Rating: 317 Authority: 320 Joined: 30 September 2021	#2 0 16 January 2023 20:43:21 With all that encryption going on, perhaps Proton could work only with TB! Professional license, but not the Home license. This is just a wild guess though...