Since yesterday I can’t send mails via Outlook, because Outlook is gone at the point “send as” :
The other two accounts are still in place. Only Outlook is gone. I still deleted the account and renewed it. And I switched back to a former backup. Still the account is gone. In Vivaldi (for example) there’s no problem …
Go to Menu > Accounts and click on the General tab for that outlook account. Scroll down to Services, tick the AirSync service and click on Save & Close.