21CN Mail vs Fastmail Masked Email

21CN Mail has no write-up on Specifiction yet; its figures are above.

Fastmail Masked Email creates a random email alias for each login, letting users give a site an address other than their real one. Using separate aliases can make it harder for companies to connect accounts for tracking. Messages to these addresses arrive in Fastmail; a masked icon marks them, and opening a message shows the label assigned to the address. An alias can be turned off if it starts receiving spam, which Fastmail says may help identify who exposed it. Users can connect Masked Email with 1Password or Bitwarden, or use their own domain; Fastmail says a custom domain is less anonymous than its shared domain but makes addresses portable. A JMAP extension lets apps read and manage addresses, though pending API-created aliases are deleted after 24 hours and do not appear in the interface. Fastmail supports two-step verification and passkeys and encrypts stored data and communications. Its own apps do not offer end-to-end encryption. Plans start at $4 a month, and a 30-day trial is available; there is no free plan. Access is available on Android, iOS, Linux, macOS, Windows, and the web.