Why did I get e-mail about Walrus DoubleCheck?
Because someone wants you to pay them --- probably you have agreed to transfer funds to an investment vehicle or a service provider.
DoubleCheck lets them be sure that you got their payment instructions securely.
Why should I use DoubleCheck?
Hijacked payments are a huge problem. Here's an example:
You are expecting to wire money to pay your lawyer.
You get an e-mail from your lawyer saying that she'd rather you use her new bank account.
But this e-mail isn't really from your lawyer, and that bank account belongs to a scammer.
You pay the scammer.
DoubleCheck neutralizes this threat
Exchanging payment instructions through DoubleCheck ensures that the right person gets the right instructions.