LinkedIn did in fact have that as an explicit feature where users would insert their email password on LinkedIn’s website. https://www.linkedin.com/help/linked

LinkedIn did in fact have that as an explicit feature where users would insert their email password on LinkedIn’s website. https://www.linkedin.com/help/linkedin/answer/5204/email-password-prompt-after-attempting-to-import-your-address-book?lang=en https://www.linkedin.com/help/linkedin/answer/5204/email-pas... > If your email provider doesn't support OAuth, you'll need to enter your email password before clicking Continue. LinkedIn will use your password only for a moment to authenticate your account. We don't store or save your email password during this process. Facebook’s feature was similar I believe. Where they stumbled was connecting an email verification feature to the code written almost a decade ago for contact import.