Try using your complete email address, not just the part to left of @. If that doesn't work, change port to 587 while keeping the full email address. Let me know

Thanks David, I had tried this. No good. Now I can't receive emails either and I haven't changed a thing. I have hunted down every single fix I can find, but no solution. Just today I've started getting the error 10060 as well. I can send and receive emails on Optus Webmail, so they have no interest in helping further. And now this - see attached image.