Might try updating Chrome and Thunderbird (Beta)

https://www.mozilla.org/en-US/thunderbird/channel/

Seems the security update delt with many e-mail certificate security issues...

Chrome was already up to date. I installed Thunderbird (Beta), but it didn't fix the problem.

I changed my default browser to FireFox (and also tried Safari). Hyperlinks in Thunderbird *do* work correctly with FireFox and Safari, but still fail with Chrome, so I have a workaround but not a solution.

Thanks for pushing me to try more things I hadn't thought of!

For a Mac running High Sierra:

This problem with hyperlinks not working appears to be coming and going with various OS updates. I am not sure exactly what is happening, but over the past few months I have seen this appear and disappear at least twice.

I tried all the things suggested in this thread and they did not resolve the problem.

Today I discovered two interesting things:

(1) Various links under "Help", such as "Release Notes" don't work when this starts happening. So the problem appears to relate to certain ways the hyperlinks are launched.

(2) Rebooting my Mac fixed the problem.

It is really annoying when this problem flares up, so we need a more strategic solution. It is virtually impossible to use an email client that doesn't support hyperlinks.

-Joe

Just found this on another forum. Success at last! Solved:

1. Open Safari Setting and change Safari to be the default browser

2. Close all Chrome instances, and reopen Chrome

3. When chrome asks you to set Chrome back to default: choose chrome to be the default browser.

Success