My employer's default browser is Internet Explorer, and her default email client is Thunderbird. Up until four weeks ago the "send link by email" in I.E. worked fine. It now starts Thunderbird, but does not launch the WRITE dialog box, nor does it pass the URL to Thunderbird. Firefox on her computer, using the "Send via email" menu option correctly launches Thunderbird's WRITE dialog box and correctly passes the URL to the new message. One query for this problem is found here: https://support.mozilla.org/en-US/questions/1157553 The suggested fixes do not work. MAPI appears to be functioning fine on the computer: Firefox (not the default browser on her computer) links to Thunderbird (is the default email client) fine, but Internet Explorer (which is the default browser) is not working properly. I have already done the suggested "fixes" that tens of thousands of people have suggested--- changing default software.