Error can't send email

Says there is no account setup, but there is and has been OK for many years. Error is since recent update.

If this is for a Microsoft account, so hotmail, outlook, live, msn etc. go to Menu > Accounts and click on the General tab. Scroll down to services and tick the AirSync option. Do that for all Microsoft accounts you have in use. Click on Save & Close when done.

Before the last eM Client update I had the choice of sending an email in Hotmail or Gmail, but now when I click on the down arrow on the right hand side of the tab showing my Gmail address it just comes down with the same Gmail address and I can’t get the Hotmail address to appear. I can still send Hotmail if I go back to Outlook and do it there, and I can still receive Hotmail both there and in eM Client, which is where I can also send and receive Gmail. It’s a nuisance because I find Outlook rather clumsy to use and prefer to use eM Client, and consequently I now have some emails sent in Hotmail and some in Gmail whcih is potentially confusing for recipients.

It is an outlook account.
I have ticked the AirSync option but now the email I was trying to send has disappeared. It is not in Sent or Draft folders.