which contained hypertext links (EML)

Can you give an example of the link you sent?

What does 'EML' mean in the context of an URL?

The links contained in the body of my email showed as hot links when viewed on my android tablet but were not so when opened in Thunderbird on my PC.

I always get a bit of a shiver when I hear the term "hot links" because it demonstrates a lack of knowledge on what a link is.

I have no idea what mail app you use on android, not do I know is it auto detects URL and makes a hyper link out of them. Thunderbird you will probably have noticed does not make the links active until you send the mail.

So to determine what is or is not happening we need to see the source of the email.

As this forum provides no way to do that, you can email me the original at unicorn.consulting at gmail dot com