Timeouts usually happen because an antivirus program is scanning outgoing mail. If you have such a program, disable its mail scanning component, or better, run in Windows safe mode to check if any program is interfering with email operations.

For W10, Shift+Restart, Troubleshooting, Advanced Options, Startup Settings, Restart, 5.

I contacted my anti virus company, they did a remote check on everything and it's not the anti-virus program that's stopping it. It's obviously a matter to do with Thunderbird. Thanks for your response any way.

Well, as has been said before, "they would say that, wouldn't they?"

Do try disabling it for yourself. Running your operating system in its safe mode should do the trick.

I saw them disabling the firewall and real time scanning, as it was done remotely. I was then asked to test the Thunderbird email. I sent an email, and the problem occurred once again. That's why the anti virus company said, it's not the anti virus package that's causing the problem. It's a bit pointless doing the same thing all over again, as it will only produce the same result.

Our experience is that "disabling the firewall" doesn't always have the required effect.

You seem happy to take things on trust and assume the outcome. I'd want to check it for myself.

I saw them disabling the firewall and real time scanning, as it was done remotely. I was then asked to test the Thunderbird email. I sent an email, and the problem occurred once again. That's why the anti virus company said, it's not the anti virus package that's causing the problem. It's a bit pointless doing the same thing all over again, as it will only produce the same result.

I saw them disabling the firewall and real time scanning, as it was done remotely. I was then asked to test the Thunderbird email. I sent an email, and the problem occurred once again. That's why the anti virus company said, it's not the anti virus package that's causing the problem. It's a bit pointless doing the same thing all over again, as it will only produce the same result.

I've disabled the' firewall' option myself and the 'real time scanning' option too, they are the only two that have an impact on this, the other two options for this are: 'automatic updates' and 'scheduled scans'. I tried it in safe mode that didn't work either.

If you have confirmed that you get the same error when running in Windows safe mode with networking, the next thing to check is your outgoing server settings. According to Plusnet, you should have relay.plus.net on port 587, Connection security = none, authentication = password, transmitted insecurely, User name = email address.

A non-secure connection might be a problem if you're trying to send on a non-Plusnet network, and one remedy would be to add your Plusnet account to a gmail or outlook.com account and send through the secure servers of those mail providers.

There should be no need to disable your antivirus (name?) real-time scanning option, but the mail scanning component, if it is an option, should be disabled.

This problem only started about 3 weeks ago. I started using Thunderbird about 9 months ago and this is the first time the problems with sending emails has happened. I'm not really tech savvy. Can you tell me in lay mans terms what I should be doing? Are you saying ditch Thunderbird and use G Mail instead?

No, I mean it's possible to send from your plusnet account through the gmail outgoing server, all done within TB. But you should first compare your outgoing server settings with the ones mentioned in my last reply.

Also, if you know what happened 3 weeks ago when the problem began, perhaps that will point to the cause. Was it a Windows update or update to your antivirus program?