Is there this kind of IRS audit?

The IRS do no send emails, nor would they address it to "dear tax payer" this is a scam

Nope, they only take the moneys.

They sent letters in 2008 for those who didnt claim the $400 extra cash. In general, if you dont claim your refund they dont inform you.

absolutely not, in fact this is probably a scam

It could happen in your dreams.

They wouldn't spell declare like that, that's for sure.

They do check returns for basic things when processed and will correct in your favor if needed. Beyond that, it's on you do line this up. And if anyone pops out of the blue - especially with such horrible English - offering your free money, that's called a scam.

This is a scam, or at best a fraudulent/misleading advertisement. Regardless, the wording of the letter is hilariously bad, so you should ignore it. Throw it away, burn it, whatever. But do not in any way contact them.

The IRS will issue notices to inform you that you made certain kinds of mistakes that are to your benefit, but those are pretty much limited to you forgetting about payments that you made. They will not send you a letter about deductions you failed to take.

no

Generally not for deductions, no, as they generally have no way to know about most of your deductions. Sometimes if you miss a credit you are entitled to, yes.