I am guessing an antivirus program problem. Do you have email scanning enabled perhaps? Many of the more common antivirus programs basically use substitute certificates to hack your mail and scan it. Thunderbird does not use the windows certificate store where they dump their questionable self signed certificates, unlike Microsoft mail. As such generally there are issues because there is a problem with the connection encryption. The certificate they use is not trusted by Thunderbird as it is not issued by an audited authority, so the connection fails.

You can make Thunderbird trust these certificates, but the instruction vary according to the antivirus vendor, so their web site is the place to look for instruction on importing their certificates to Thunderbird.

So in the first instance I would suggest disabling mail scanning in an antivirus product (defender has no mail scanner) and see if you see an improvement.

Hi Matt, and thank you for your reply.

I have tried what you suggest, but it still wouldn't load. I did used to have it about 12 months ago, but at the time I tried Thunderbird then it had a few glitches that I wasn't happy with, so returned back to Outlook, deleted my accounts for Thunderbird and deleted the download. A friend suggested I try Thunderbird again though, as it had recently become much better and he had returned to it. I like everything about it so far, but just can't get Hotmail to load, so unfortunately it's unusable for me. I need to have my Hotmail, Gmail and Outlook accounts on there (surprisingly, my new Outlook account does load, which is a Microsoft product too).

I'm out of ideas at the moment, but will persist when I have a bit more time to look at settings etc... or get someone that knows more about that than I do!

Could you please do the following?

1. Open the menu > Help > Troubleshooting Information, then click Copy text to Clipboard.
2. Go to https://pastebin.com, paste the info from your Troubleshooting Information page, use the Create New Paste button to create a page containing your info, then copy the resulting URL (address) of the page created.
3. Open a reply to this post, and paste the link to your troubleshooting information you just copied.

Next, we'll need you to provide answers to the following questions:

• Does Thunderbird work in troubleshooting mode?
• Do you use anti-virus and firewall software? What is the version?

Hi I am using Defender so no mail scanner but get 'unable to log in at server. Probably wrong configuration, username or password' when trying to set up a hotmai account. It was previously working but I changed my Microsoft password. I have input the new password, does not work. I have deleted the account to try to set it up again. I have tried POP instead of IMAP. I have tried varied manual configuration options. I have uninstalled and reinstalled Firefox but I seem to get my old settings back. What next? Thanks, Nick