> The fact that “Message” meant too many things led to it being renamed as “Email”
No. No no no no no. 'Email' means even more things than 'message'.
1. Address: "What's your email?"
2. Synonym for 'send': "I can email you there. "
3. Message body: "Let me know when you've got the email."
1. That's an email address, not an email.
2. That's a noun-ed verb - context generally makes it obvious when verbs are used rather than nouns. "I can email you" is a shorthand for "I can send an email to you".
3. That's fine - a mail client / server would never confuse these as the body is very obviously a property of most any representation.
In the same way that I'm not concerned that my postman has never delivered a fence to me, or written on a bulletin board system, I think we can cope with this name being the appropriately sensible one.
Have I misconstrued your argument?
Your postman doesn't deliver fences to you, he posts post to you. In a similar way, instead of using the word 'post' all the time, a sensible design for an API would want to have a person deliver a message.