Have you ever received emails for cheap software? Are they legal?

Yes I have, and no they are not.

To go further: even if they were you should not use the services.
NEVER reply to spam and NEVER EVER buy anything from a spammer.

Some are some aren't it depends on the supplier like if their based in eastern europe (Moscow) they usually are illegal. Sites based in UK, USA are usually ok. Here is a great Cheap Software site i found recently which sells cheap software. I bought windows xp pro and recieve my order as promised within a few days.
here's the link: Removed. Links to pirated software sites are prohibited. Daniweb Mods
Enjoy.

Looks fishy. Proudly displaying a CDR on your frontpage doesn't inspire my confidence in their legality...

Prices are also too low to be legit, below even OEM and educational prices (and those are available only under strict conditions which these guys don't seem to enforce).
And of course in his FAQ he mentions a lot of incorrect things about downloading but nowhere mentions it's illegal...
His method for installing Windows XP is invalid for legal versions which boot from CD, his software does not ship in the original packaging and does not have manuals.
I guess you got CDRs?
He will deliver on CD or DVD on order thus he burns his own which reputable dealers NEVER do as they get complete and legal packages from the manufacturer.
He says you shouldn't register the stuff you buy from him with the manufacturer (guess why, the manufacturer will then know you have a pirated version...).

Sorry, but you got ripped off by someone selling pirated software. I suggest you contact Scotland Yard's computer crimes division.

No i don't think i'll be contacting anyone because i got a good service, i know there's a myth out there about pirates but it's common place now you'll agree and frankly hearing the word pirate now days don't mean anything to me. But what i will point out to you is the most important of all can you trust them yes you can and that's saying alot nowadays, plus this guy is not like the real criminals who actually try to cover up their operation by charging the same price of the real product and cover the cd with a printed forged label. At least this site is open (honest) so you can make your own informed decision.

Thanks for your reply.

Might not mean anything to you, but it means a heck of a lot to us. Any further posting of links to pirated software websites will be removed and persistence will result in suspension of your account.

I think the original question has been answered - don't trust those emails one aota. Bin 'em and buy original software from your local or trusted online dealer.