I haven't had, or heard about, any problems with sending after the 1809 W10 update. What is more likely is that you have a security program scanning outgoing mail, and that program is not fully compatible with the W10 update. If you have an AV set to scan outgoing mail, disable that feature and see if sending works. Or, run in Windows safe mode to isolate startup programs such as AV.

Hello,

I turned off my McAfee real time scanning and firewall, then sent a test email to myself, but problem remains. Email times out before completing the operation.

Other AV, CCleaner and Super Anti-Spyware need to be invoked to check on problems, so these should not have an impact on the timeout problem

Turning off the real-time scanning is neither necessary nor recommended. It's the email scanning that should be disabled. Best way to rule out 3rd-party interference is to run in Windows safe mode.

Unfortunately, when I went to safe mode with connections, I still had trouble connecting to internet. I was not in "airplane" mode or tablet" mode or any of these.

So I was not able to try sending an email. in safe mode.

Do you have a VPN? If so, that will surely interfere with sending mail. Also, since sending doesn't work in Windows safe mode, it appears to point to a network issue such as a router firewall blocking outgoing ports, or a faulty network adapter driver. Perhaps you can try it on another network. Sometimes even restarting the router/modem can fix problems like this.

I have VPN on my homepage, and selectively use to open a few reports, but nothing routine or automatically invoked.

I have disconnected both router and modem, with negative results.

Note that I have been sending emails using my webmail service the past couple of days.

Sending through webmail uses a different process than sending with TB. Which VPN, and do they give instructions for sending over smtp with email programs? Try disabling the VPN entirely and see if it makes any difference.