the problem arises from the outfit who sent you the offer. They've already pulled your credit history and know your SSN. It's all in their file.

so if they're not very careful … here's what could happen …

[omitting a vital step or two here to not give away how to do the whole thing.]

thief steals your mail and sends in the credit card offer himself. He gets the card in the mail when it comes [come on -- you aren't home are you? you're at work. is your mailbox locked?? thief steals the card when it comes]

thief also steals the welcome letter, etc. [his only risk is Saturday when you might be home instead of at work plus/or some nosy neighbor who wonders why Joe Unknown is opening your mailbox.]

you are clueless — he has a credit card in your name and on your credit.

viola!! he's off to the races. how much can he charge in small, ordinary situations before the card is deactivated?

your credit is paying for all of his gas, grocery store, etc. purchases and maybe some new electronics if he can find a store that doesn't check for photo ID.

here's the real kicker — if your mailbox isn't locked and he intercepts the original offer and following mail, you'll never know he did anything at all until the account goes unpaid and the bank's people call the fake phone number, get the wrong person, and then go searching for your real phone number.

that could be thousands of dollars later and all on your credit!!
References :
ex-banker