cashback discount e-mail is it safe?

No!

Haha, doubt it!!!

My rule is, never respond directly to unsolicited emails!
If I had wanted to contact you, I would have, but I don't!!!

In saying that, I once received an email from Amex, with a contact number to call, saying there had been a fraud on my card. Someone was buying sex videos in NY.

A scam, I thought! I ignored the contact number given and called Amex directly on the number on the back of my card.
Are you calling about the fraud?, asked the agent. We have stopped your card.

So it actually was genuine!

No yet another scam.

I am the lucky one also.
I have nearly £20,000 in my Bitcoin account, pity I don't have one

£6.50 ? Surely nobody would go through the rigmarole to receive goods worth that paltry amount, it is just a means of getting your bank details.

If in doubt do nout.

If anyone contacts you it is always a scam.

Some years ago I had an unsolicited call from Barclays, so they said, asking whether I’d be interested in online banking. I gave a cautious yes, but once he started asking for personal details I hung up and got the number from 1471.

I then phoned Barclays Fraud dept. to inform them.
Lo and behold, it was genuine!
I’m sure they would never do such a thing now, but you never know.

I had a letter about compensation for mis sold shares I had never heard of. Turned out they were from my dad's estate and eventually I got £200 back.