not able to get messages from Office365 account, "Off line mode" remains activated without message

My account was OK with office365 till yesterday.

Since yestarday midday, I no longer receive emails (but some of them goes out).
I got once 1 error “connection rejected by server” but other times no message.

I just identified that eMClient was in “Off line mode”: why is it kept even when manually requesting synchronization? Why do you try (and succeed) in synchronization calendar but not mail olders?
Changes to online, emails go again, in and out.

Usually when you can send but not receive, the cause is the anti-virus application. That would also account for the calendar being synced but not the messages. Disable your anti-virus application and see if there is any difference.

Offline mode can be caused by a bad Internet connection. At home on my crappy rural connection it happens regularly.

it restarted without any reason just before noon… Checking update status for antivirus: last one was at 11:40am today… Thanks for the tip which may help others in similar situation.