V8 sendmail contains the internal ability to convert 8-bit MIME message content into 7-bit MIME so that mail can be transported through non-8-bit gateways. The methods used and the circumstances required to trigger conversion are described under the EightBitMode option (EightBitMode).

Defining MIME8TO7 to a value of 1 causes support for conversion to be included in sendmail. It is defined as 1 by default. To disable the inclusion of conversion code, add a line like the following to your Build m4 file:

APPENDDEF(`confENVDEF', `-DMIME8TO7=0 ')
                                    
                          exclude support

One side effect of defining MIME8TO7 to 0 is that it causes all MIME support to also be excluded. Unless you have a compelling reason to do otherwise, we recommend that MIME8TO7 remain enabled.

If you are running a precompiled sendmail binary, you can use the -d0.1 debugging command-line switch (-d0.1) to determine if MIME8TO7 support is included (if it appears in the list, support is included).