It is therefore unfortunately necessary to make several such alphabets available. Japanese and Chinese scripts are usually represented with multi-octet character sets. To make sensible use of an extended character set in the presence of several possible sets as above, mail systems have to exchange both the 8-bit characters themselves and the directions for their interpretation. Merely including 8-bit characters is prohibited by the standards, and gives no indication of the intended interpretation of the characters. Cooperating mailers agree that they will accept and transfer a particular message without damage to 8-bit data.
Additional capability is required of site and departmental mailers to enter into the negotiation.
Although products are available and the number of managed mailers deployed is far less than the number of User Agents, a systematic upgrade within any mail management domain is likely to involve significant effort and disruption to service. The mailer might attempt conversion to a 7-bit MIME encoding for delivery. MIME MIME is specified in RFC 2045 and the RFCs which follow it. MIME is widely deployed. In the following fragment of a message as transmitted, the MIME header indicates an encoding and a character set.