8BITMIME

8BITMIME (RFC 1652) is an SMTP extension standardized in 1994 that facilitates the exchange of e-mail messages containing octets outside the seven-bit ASCII range. Prior to the availability of 8BITMIME implementations, mail user agents employed several techniques to cope with the seven-bit limitation, including binary-to-text encodings and UTF-7. However, each of these workarounds necessarily inflates the bandwidth of non-ASCII transmissions.

At least the following servers advertise the 8BITMIME extension:

• Apache James (since 2.3.0a1)[1]
• Courier Mail Server
• ESMTP [2]
• IIS SMTP Service
• Lotus Domino
• Maillennium [3]
• Microsoft Exchange Server (as of Exchange Server 2000)
• Novell GroupWise
• Postfix
• Sendmail (since 6.57)
• SubEtha [4]

The following servers can be configured to advertise 8BITMIME, but do not fully implement the standard:

• Exim (eight-bit clean, but does not translate eight-bit messages to seven-bit when relaying to non-8BITMIME peers)
• Microsoft Exchange Server 2003 advertises 8BITMIME by default, but relaying to a non-8BITMIME peer results in a bounce
• qmail (does not translate eight-bit messages to seven-bit when relaying to non-8BITMIME peers, as is required by the RFC [5], [6])

As of June 2005^[update], the following servers do not implement the extension:

• Microsoft Exchange Internet Mail Service (through version 5.5)
• Netscape Messaging Server 4.15

[edit] See also

• List of mail servers
• RFC 3516, IMAP4 Binary Content Extension