The message body type is described under the -B command-line switch (-B). The B line in the qf file stores whatever the body type was set to, either from the command line or by the SMTP MAIL command. The two usual body types are 8BITMIME or 7BIT.

The form of the B line is:

Btype

There must be no space between the B and the type. If the type is missing, the body type becomes the character value zero. If the entire B line is missing, the default is 7BIT. If type is longer than MAXNAME as defined in conf.h (MAX...) when compiling sendmail, it is truncated to MAXNAME-1 characters when the qf file is read.

Note that the type must be either 7bit or 8bitmime. Anything else will not be detected when the qf file is read and might eventually cause the ESMTP dialog to fail:

501 <sender>... Unknown BODY type badtype

This error will be reproduced at every MX site for the recipient until a site that does not speak ESMTP is found or until the MX list is exhausted.