What Thunderbird is trying to retrieve is the welcome page that usually appears when you start Thunderbird, before you preview a particular message. It sends this request (with the parameters set to match your installation) and gets back the second address:

• https://live.mozillamessaging.com/thunderbird/start?locale=en-US&version=24.4.0&os=WINNT&buildid=20140316131045

• https://www.mozilla.org/en-US/thunderbird/release/start/?uri=/thunderbird/start/&locale=en-US&version=24.4.0&os=WINNT&buildid=20140316131045

If I intercept the connection and generate the error page, the link to add an exception doesn't pop up the usual dialog, which makes it hard to investigate.

This probably is a system-wide issue. Have you noticed any certificate issues in Firefox? If not, your security software may have added a certificate to Firefox that allows it to stand in the middle of your secure connections, but overlooked Thunderbird.

To gain some insight into that theory, could you open one of the above links in your preferred browser and inspect the certificate? In particular, what is listed in the "Issued by" or "Issuer" section. To do this in Firefox, click the green or gray lock icon to the left of the site address in the address bar, click More Information, then View Certificate.

When you are connected directly to www.mozilla.org, you normally see "DigiCert High Assurance EV CA-1". What does yours show?

Thanks for responding!

I opened the links you suggested but did not get any of the things you said to look for. I get the same message in Firefox when I try to log in to Comcast.net which is my email supplier. Cannot do the exception procedure.

In Thunderbird, clicking on the exception doesn't do anything. What next?

Don't understand any of this.

When you open the page in your browser, can you find the lock icon in the address bar and click it to get to the security certificate? I have attached a series of screen shots showing what I mean and where the issuer information is in the certificate viewer.

I looked under options/advanced/certificate manger/your certificates and no certificates are listed. This page is blank. Under people and others is also blank. There are many listings under servers and authorities. Does this help?

WES

I think "Your Certificates" would be for certificate you use to sign your outgoing emails. Probably the "Servers" tab would have exceptions that were saved successfully.

But for the moment, I want to know what you see when you access secure sites in your browser, since presumably (?) Thunderbird is seeing the same one.

Yes I see the little icon nest to the address bar. When I click on it, a window opens with a message that this site does not supply identity information. Your connection to this web site is not encrypted. When I click on the more information tab it opens another window which gives the page info.

Oh, if it says not encrypted, somehow the link switched from HTTPS to HTTP. Could you try this one again:

https://www.mozilla.org/en-US/thunderbird/release/start/?uri=/thunderbird/start/&locale=en-US&version=24.4.0&os=WINNT&buildid=20140316131045

I retried your latest link in Firefox and it said this connection is not trusted. When I open the link in Explorer I get the Welcome to Thunderbird site.

Okay, great. In IE, click the lock icon to call up the certificate and check the Issued By section. What's there?

It says issued by: DO_NOT_TRUST_FiddlerRoot

That issuer usually indicates an unwanted program named BrowserSafe, Browser Safeguard, or Safeguard. Could you check the Windows Control Panel, Uninstall a Program. Clicking the "Installed on" column heading will bring the most recent items to the top. This also is helpful in revealing unexpected bundled programs installed together.

BrowserSafeguard was installed on 3/3/14. What now? Remove it?

Yes, I'm pretty sure you do not want BrowserSafeguard intercepting your secure connections to "filter" them and whatever else it might be doing.

I am new at posting on the forum and couldn't figure out how to get back after rebooting this morning. Hopefully, this message gets back to jscher2000.

After deleting BrowserSafeguard and restarting, everything was back to "normal" on Thunderbird startup. On startup this morning, everything still okay. I consider the issue solved.

Impressive how you walked me through the solution. Would never have figured this out myself. Can't thank you enough for your patience and outstanding help. Anything I can do to help you? Fill out survey? Name it!!

Many thanks,

WES

Hi WES, thank you for reporting back.

I think there probably is a dialog somewhere in IE's options that will allow you to remove the trust for the "do not trust" certificate. Not sure where that would be listed.

In IE under Internet options on the Content tag I click on certificates and it opens to Personal tab. The entire listing shows all certificates issued by DO_NOT_TRUST_FiddlerRoot. There are 150 certificates there including several for Mozilla, Google and most of the sites I visit from time to time. Even has certificates for my brokerage firm and many of sites I visit and purchase items from. All certificates expire on 3/**/2024. The other tabs are Other People which has no certificates. Another tab is Intermediate Cerfication Authorities which has 18 certificates of various Issuers and various expiration dates. The last tab is Trusted Root Certificate which has over 200+ certificates, all from various issuers and various expirotion dates. I am not sure what to do here. I don't normally mess with this kind of stuff. Afraid to delete because I don't know what effect it has on IE. What happens when you delete certificates?

I guess you work for Mozilla, so I understand if you are reluctant to give advice on this. Thanks for what you have already helped me with.

Actually, I just volunteer here...

Do you recall adding 150 exceptions in the past month, or did BrowserSafeguard sneak them in behind your back? I would remove the exceptions for sites where you enter or retrieve sensitive data.

I had the same problem. Followed the advice and deleted Browser Safeguard. Rebooted and all iss normal!

Thanks for the great advice. I'm running Windows 8.1 with Firefox and Thunderbird. Email is with Cox.net.