Sorry to keep on about this topic.
But to be fair to British Gas, they do offer sales/ rewards promotions...However they do also give a very clear message for the user to opt out of these email notifications, if required.
British Gas have their own domain @britishgas.co.uk and do not use gmail for their email correspondence as is shown in this email. It may be the case that British Gas do as you say but this is obviously a scam.
@Will168 Sorry to remove your laughter but you clearly haven't read or understood my post. Nowhere did I say that it was sent from a gmail address. I wanted some sanctions taken again the idiot who sent it to me because he/she has a bt email address.
Of course, phish emails will be sent using Spoofed email addresses, whether they are genuine addresses or not. They won't come from that address - so ISPs or email providers will not delete the address, unless it can be proved without a shadow of a doubt that it has come from that particular account. Even then, the account could have been hacked.