|When the MIME standard was defined, it was carefully designed so that MIME data would not break older mail software. How was this done?
Note: Many students answered with description of the MIME-Version header field. But that field does not solve this problem, since the older mailers do not understand this header field, they do not know what MIME is, since they were written before MIME existed.This answer shows a fundamental misunderstanding of the problem in the question, which was how old software, defined before MIME was known, would treat MIME messages.
However, there are certain smart e-mail routers, which know, for each user, the capabilities of the client used by that user, and which will convert MIME messages to a format which the client can handle. With this method, the MIME header fields can help to avoid breaking older mail software, but this works only because some of the software (the mail routers) does understand MIME.
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