Comment by js2

Can you please clarify whether this is only an issue if I reply to an email sent to one of my HME addresses or whether you can unmask any HME address w/o needing a reply from the recipient.

Can you also clarify whether it matters what the forwarding address is? e.g. whether my HME addresses forward to an icloud.com address (e.g. js2@icloud.com) or say a personal domain associated with my Apple ID (e.g. js2@example.org).