Separating Cloudflare Accounts and Billing per Customer — Why Gmail Aliases Get Rejected and How to Mint Real Addresses with Google Workspace Aliases or Groups

You want a separate Cloudflare account per customer so billing is separated. Trying to mass-produce accounts with Gmail +alias fails with 'A variation of this email address is already taken.' Creating another account needs a real, distinct email per account. Here is why, and how to mint those addresses with Google Workspace aliases or Groups.