Setting up General Email (IMAP, SMTP) fails

Some of us occasionally never get that far. Unfortunately, the conditions which lead to this dysfunction have never been fully discovered, let alone documented. I understand that it never happened at Jolla in the QA process, and “there’s something wrong with General Email accounts in SFOS” is not the nicest bug report I can think of … but regardless, it is at least annoying and made some of us think IMAP/SMTP accounts would be entirely unsupported. “It worked OK back in SFOS 1” doesn’t help those who joined later.