The email you received does not have the correct html that is required to turn the http://etc into a link. It seems they have only added it as text. So you can blame that on the person who created/sent the email. If you select email to read and then click on 'More' and select 'View source', you will see that http part is not enclosed in the correct html format which creates the link. The url has been only added as text. Perhaps it would be a good idea to inform the sender that links are not including the correct formatting that actually makes the text a link. It is expected that the correct html formatting would be included in a html email. I have ordered items before from Amazon and I can verify that in those emails the links have been created correctly. 'View' > 'Message Body as' > 'Original HTML' does not necessarilly underline links as it depends upon the html css, but they would all appear in a different colour and work as expected. 'View' > 'Message Body as' > 'Simple HTML' usually shows links in blue colour and underlined. NOTE: Links sent in plain text emails will not have the correct formatting by default and so Thunderbird inserts it. '''Workaround:''' If you change the 'View' > 'Message Body as' to 'Plain Text', then you should find the link text change colour to denote it is a link; it will be underlined and clickable. There has been some recent mention of this issue by another user, so I had researched and found an old bug report, where the sender is not including the correct html code. The suggestion is to start checking for that in html emails. This is the bug report: https://bugzilla.mozilla.org/show_bug.cgi?id=920560 I notice that some of the http url does not have the www. in the link text, there was another bug mentioning this, but you would need to test those links by using the workaround I mentioned above, to be sure whether another bug is also effecting things.