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]
Citadel (since 7.30)
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

See also