Hi info1545,
Thanks for reaching out to us here. QuickBooks Online requires multi-factor authentication to ensure your company data remains secure. When logging into your account, you'll be asked to verify your identity by entering a one time passcode, sent directly to your phone. However, you can choose to 'sign in another way', and select the option to send it to your email.
If you have any other questions, feel free to reach out. We would be glad to assist!