The point is that iMessage lets you send to any contact and it’s not clear if it will send to their iMessage, which uses email as an identifier, or to their actual email inbox through mms.
It is clear in a non group conversation, since the contact will show up in a blue color in the “to” field.
In an MMS, it could be unclear, but only if you choose to put an email address in the “to” field. If you know it is an MMS, and you only use phone numbers, then it will not be an email.
In an MMS, it could be unclear, but only if you choose to put an email address in the “to” field. If you know it is an MMS, and you only use phone numbers, then it will not be an email.