Can you check Thunderbird’s Connection settings (Tools > Advanced panel > Network & Disk Space tab > Settings) and make sure "No proxy" is selected?

As for Mozbackup, I would advise not to use it any longer since it is no longer maintained, and several users have run into issues when restoring.

I did try selecting "No Proxy" and that did not help.

Instead of Mozbackup I simply copied and pasted "Documents and Settings\Barry\AppData\Roaming\Thunderbird" from the computer where it works fine to the one where it hangs up as described above but this did not change the behavior.

The status line should quickly changed from "Connected to ...." to "Host Contacted...." but it remains on "Connected to ...." so this leads me to believe there is maybe a setting associated with the networking that somehow has changed. I just cannot find anything different between the two machines. I also find it strange I can send emails but I am apparently not even able to connect to the incoming server to receive emails.

Tonnes, do you represent Mozilla? I would like to get this problem fixed and I do not mind paying Mozilla for a support call but there is no obvious way to do so. I tried calling their customer support number but got someone in India that spoke fluent English but it was impossible to meaningfully communicate with her. In addition she wanted to access my computer and I did not have the confidence to feel comfortable she would not screw something up.

I have been using Thunderbird ever since Outlook Express was dropped, liked a minimal clean email client, and want to avoid Outlook if I at all can. The W10 Mail is to minimal to be useful.

Thanks.

Are you using POP settings as decribed here, i.e. are you sure pop.mail.yahoo.com, port 995 and SSL (not STARTTLS) and your full email address for the username is set? Here you can find a clear article for setting it up using the automated method, even though port 995 is not mentioned there. Note that it says to enable POP access using webmail, where Yahoo’s page does not.

When unsuccessful, it makes sense to assume there may be some requirements with regard to the sender email address as well as the SMTP server. Therefor try to use a proper sender address (configurable in Identities), and also make sure to use the SMTP server as described in the Yahoo help page. The idea is that you may be accessing Yahoo from another ISP now, so even though the SMTP server may seem to work as expected or in case you are using one that’s not not affiliated to Yahoo at all, this may be important. I have no experience with using ATT/Bellsouth/Yahoo accounts myself, but please have a look at this question for more info.

When unsuccessful: since you are familiar with Thunderbird Profiles, you could back up the profile folder (if needed), remove the account in Thunderbird and recreate (add) it and then restore the local email content, but without restoring the prefs.js file. You may be familiar with the fact Thunderbird is set to delete mail from the server after retrieval by default when using POP so either change that option first (or set it in offline mode after setup completed to avoid connecting), unless this is no issue. I’m very curious to see whether the automatic account setup uses the same ports as descibed in the article.

For support: of course I understand your concern, but I do not represent Mozilla, as with anybody else on this support forum. Since Thunderbird is an open source product, there is no official customer support either so you did the right thing by not trusting the person you talked to a phone number possibly found on the web. Also, no-one should ever ask for money with regard to offering support for Thunderbird or any other Mozilla product.

Please let me try one last time.

All the settings are correct and previously worked fine. In fact, I have a second computer in the next room, attached to the same Comcast RG, same setting and Thunderbird works fine on it.

It appears to me, from the information in the status line at the bottom of the screen, Thunderbird is indeed connecting to the POP server because it says "Connected to pop.att.yahoo.com...". It appears, for some reason, my computer is not now responding to or handshaking with the server as "Host contacted, sending login information" should immediately appear next but does not because "Connected to pop.att.yahoo.com..." remains in the status line.

So, assuming all the settings are correct, and I am sure they are, what is preventing Thunderbird from responding once it does connect to the email server? Is this a W10 thing? I did try disabling completely eset but to no avail.

Thanks for your patience.

The fact you are using Eset might be very relevant, especially in Windows 10. Are you using it on the other system?

- Please have a look at this article first. If interested, there are other similar ones to find. - Then try to disable SSL scanning (or SSL protocol filtering) in Eset. If you run Eset on the other system, check for identical settings. - If that doesn’t help, personally I would uninstall Eset, reboot and reinstall it since that should be the preferred order to make security software do its job properly. - If preferred, you could also import Eset's certificate into Thunderbird manually after exporting it from Eset.

Please understand the fact that if Thunderbird or any other email client worked fine before, there is no guarantee it will as long as updates of either WIndows, security software, add-ons or Thunderbird itself take place. In particular security software can be a culprit with regard to certificates.

Good advice!!!

I disabled "application protocol content filtering" and that solved the problem. I then re-enabled it and excluded Thunderbird. Although Thunderbird now receives and sends email without any issue, I do not know if I removed protection that is important to have.

BTW, I did first uninstall and then reinstall Eset but the problem returned as soon as I reinstalled it. I don't have a clue how to "import Eset's certificate into Thunderbird manually after exporting it from Eset" other than I would manually add the certificate under "List of known certificates".

Thanks again for the good advice.