What network connectivity states are detected as "offline"?

[Soccypowa]

Hi simple question, long story behind it.
When travveling recently, haven't been a Thunderbird user for that long, I was composing an email offline, or to be more specific I realize now, composing an email at a state that for me equals as offline, Thunderbird is of an other opinion. So I was att the airport, not connected to WiFi, pretty offline if you ask me, composing a pretty long email to a friend and Thunderbird starts nagging about not being able to save to my drafts folder on my IMAP account. Ok, pretty annoying.
Safe at home I try to figure out what is going on, I mean it is pretty annoying with that pop-up interrupting my composing. I found that obviously Thunderbird has an offline mode, something that I directly thought must be automatic in some way, I mean if my device can't connect to the account I am offline, right? Obviously that is not the case. In my troubleshooting I found out that if my device, a Thinkpad, is in "Airplane mode", Thunderbird detects this as offline and starts in such mode. But funny thing is that when started and not connected to any WiFi, that is obviously detected as Online, even though I'd say common sense dictates the opposite.

Is there a setting I might have missed? Or can anyone describe the actual logic behind this? I mean Airplane mode and not connected to WiFi are pretty much equal when it comes to connectivity....

[DanRaisch]

It may not seem immediately intuitive but I think I see some logic in this. Airplane Mode is a user selected status that would mean that the user is aware there is no Internet access available by their own choice and thus Thunderbird would be off-line. The absence of wi-fi, on the other hand, could be intermittent and the user might not immediately be aware that they are off-line. Thus an alert from Thunderbird might be appropriate to allow the user to take corrective action, of which one possible option would be to put Thunderbird in off-line mode.