My $0.02 is that users should be able to self-help. If they have a log, a log viewer application, even a mail UI that gives them a hint of what’s going on, then all the better.
Mail has always been a black box in Haiku.
Think about it - if there’s an app named ‘Log Viewer’ in the Applications directory, and a user open it, and sees a log titled ‘Mail’, and it states “username error”, “password error”, etc, then said user may have a fighting chance of solving an issue themselves.
Even macOS has the Console, and that sells itself on being user-friendly…