In many cases, just citing the URL will do the trick. You'll see that this site, and maybe your browser, see that is an URL and magically make it clickable. Many email clients will do the same, though it appears that a recipient using Thunderbird won't see it as a link if the message is created using HTML coding and doesn't have explicit tags to make the URL into a link. If you're using HTML, then compose your signature as if it was an email message, using '''Insert|Link''' to add a link that connects to your site. Save the message as an HTML file and in account settings, set it up to use that file for your signature. Under the bonnet, it is simply setting up code like this: <a href="www.pleinairpainters.co.uk">Click here</a> which would appear like this: [http://www.pleinairpainters.co.uk Click here] Insert whatever text you want to show in place of my "Click here". This is the simplest possible form; you can add other embellishments such as colour, typeface, alignment etc. A common technique is to insert an image (usually a company logo) and set it as the "click here" element, so a click on the image will open the URL. Alternatively, instead of creating an HTML file, you could use that HTML code snippet directly in Thunderbird's account settings, where you can set up a signature. A cautionary word; when composing a message, Thunderbird will show links but won't make them active. So to test the link, you need to view your message as a draft, in the Drafts folder, or send it to yourself and view it in the Inbox.