Are you using a web based email client or are you trying to use Mozilla Thunderbird?

If you are trying to use Thunderbird, please post this question on the Thunderbird support forum. This is the Firefox forum, so the users may not be able to provide efficient support for your issue.

Webmail sites like Yahoo, Outlook, and Gmail offers slightly different features on different browsers.

If the URL is not automatically "linkified", try selecting it and then clicking the insert hyperlink button (or similar button) on the email editor's toolbar. The button usually will have an icon with one or two links of chain. This either will immediately convert it to a link, or will show a dialog allowing you to specify the address and visible text (if different from the address).

Since each mail site is different, if you want to mention which one you use, a volunteer with an account on the site can take a look and recommend the easiest way to do it if you don't find that button.

Make sure you are using html, and not normal text. Also, after entering the link, press <enter>

Try to select the link text (URL) with the mouse before clicking the link button. You can also send a copy to yourself (own email address) to check if it works.

Wesley Branton said

If you are trying to use Thunderbird, please post this question on the Thunderbird support forum. This is the Firefox forum, so the users may not be able to provide efficient support for your issue.