I don't know about gmail vs outlook, but I think security is often a valid concern. B2B products are usually built with a heavy emphasis on the security side of

I don't know about gmail vs outlook, but I think security is often a valid concern. B2B products are usually built with a heavy emphasis on the security side of the security-convenience tradeoff. B2C products tend to be more convenience focused. You can have a B2B or a B2C product that is both convenient and secure, but that certainly isn't guaranteed, particularly for young products. For instance Slack is great IMO, but they only introduced bring-your-own-key earlier this year (a requirement for security-serious companies).