Shocked, I tell you.

You cannot use the new Outlook app without syncing these data with Microsoft’s servers, i.e. your usernames and passwords are sent to the company’s cloud servers. While the data is sent using TLS, the IMAP and SMTP username and password are sent to Microsoft in plain text. This could allow the company to access your emails, and share the data with third-parties.

Not only that, but sending usernames and passwords in plaintext allows for MITM attacks.

So obviously not to everyone’s taste but if you have access to iCloud+ email, your mail isn’t scanned for sale (as per their US privacy agreement anyway), you get randomized email addresses available to give to places that you think might be spammy and you can link a domain to your account, although you’re only allowed 3 email boxes per user in your family per domain. Works well for me so far. Mind you because of photo storage size and devices backups I’m up to $3/ month from the original $1/month when I started.

Plus with Advanced Data Protection a lot of iCloud info is E2E encrypted. (Not email tho.)