Is this all addresses? I have 31.6.0 and it works. Try as I did to send yourself a mail with an address. It doesn't show mailto: but its click-able.

Thanks for your reply, Gnospen.

I have now realised that the received emails (with the unclickable email addresses) were from the same sender. They were created and sent from my mobile smart phone using an Android App called Type Mail (formerly know as Blue Mail) which I have recently begun using.

In Thunderbird, when I examined the message source, of emails sent from Type Mail, I saw the following (as an example -- substituting [square brackets] for <angle brackets> so that text does not get interpreted as HTML in this post)...

Content-Type: text/html;

charset=utf-8

Content-Transfer-Encoding: 8bit

[p dir="ltr"]Test new version/p [p dir="ltr"][font color ="#006970"]Sent from a Mobile Device/font[br] [font color ="#006970"]Preferred Email: /font[font color ="#006970"][b]Someone@provider.co.uk/b/font[font color ="#006970"]/font/p

...As you can see, there are no [HTML][HEAD], etc, /HEAD/HTML tags to enclose the message text -- resulting in the message not being recognisable as an HTML message .

I will feed this back to Type Mail to see if they can fix it. If I read emails created/sent from Type Mail within Type Mail, they look as they should (with clickable email addresses), but this seems to be because Type Mail appears to apply its own formatting -- a bit like Thunderbird's View/Message Body As/Plain Text approach.

Thanks again for your reply and suggestion.