Links open using whatever your computer says is the default program to use.

• https://support.mozilla.org/en-US/kb/hyperlinks-in-messages-not-working

Thunderbird program and Thunderbird Profile folder are two different things. They are not stored in the same place. eg: In Windows OS, Thunderbird Program is usually stored in the 'Program Files' or 'Program (x86) Files' folder.

The Profiles folder containing the profile name folder with all emails etc will be in the 'Appdata> Roaming > Thunderbird' folder. This means you can uninstall and reinstall the program without effecting the Profile folder.

Usually, uninstalling and reinstalling the program has no effect on most problems as they are usually related to how the computer itself is setup to deal with those requests or something within the Profile itself, hence why it is always advisable to keep a backup of your 'profile name' folder.

http://kb.mozillazine.org/Profile_folder_-_Thunderbird

In computer 'Control Panel' > 'Default Programs' Check all the following:

'Set your default programs' Make sure Firefox is set as default.

'Associate a file type or protocol with a program' make sure you have all the following using Firefox.

• .htm
• .html
• .mfp
• .shtml
• .xht
• .xhtml

Protocols:

• FTP
• HTTP
• HTTPS

'set program access and computer defaults' select: 'Custom' and click on drop down arrows

If Firefox is not open: select 'Mozilla Firefox' and 'Enable access to this program' do not select any other option If Firefox is currently open then select 'Use my current Web browser' - but make sure there is only 'Firefox browser open and not eg: IE or Chrome as well. Personally I always close the program and then make sure it is selected in this section.

Thanks Toad. I'm running this in Ubuntu and the default browser was set to Thunderbird. I don't know why either. Have now set it to Firefox and that's it fixed. Thanks for your time and contributions.