Custom domain - IMAP settings
I have a custom domain on iCloud and am attempting to set up IMAP through third-party apps. However, the SMTP connection just errors. When using the personal @icloud domain there is no issue connecting. It is then not possible to select the custom domain as the other accounts are not pulled through.
Are custom domain emails only accessible from apple mail apps and icloud.com?
MacBook Air (2020 or later)