Beginning with V8.7 sendmail, you can set the EightBitMode option (EightBitMode) to m (mimefy) to force all unlabeled 8-bit mail to be converted into MIME-labeled mail.

You can suppress this conversion for particular delivery agents by specifying the F=8 delivery agent flag. This form of suppression has the effect of setting the EightBitMode option to p (pass8) for an individual delivery agent.