"Email Diamant" is roughly translated "diamond enamel". It's proudly French and made since 1893.
Normally this Museum does not feature boxes that pastes come in, but this time I had to show you a closeup of the bullfighter guy, since he's in full color on the box. He's a happy user of the paste!
The taste is different - with a nose of anise, to use wine terms. The paste is indeed very red - it almost stains my toothbrush.
I love the description. The translator from the original French did not have a good command of English: it "respects" the tooth enamel. And it has "natural light reflectors". (I'd recommend regular users riding their bicycles at night with their mouths wide open.)
If you're in the USA and desperately want to try some, it's a bit expensive: $19 from here. (I'd recommend instead that your sister who lives in Belgium bring you some when she visits.)
Finally, you were hoping for a joke about toothpaste relating to e-mail. Sorry to disappoint you.