SMTD-721 — Incorrect multipart MIME boundary definition
The MULTIPART BOUNDARY argument value has limited length and character set allowed in the RFC. Argument present in the Content-Type: header of the part printed violates some of these rules.
Mail is rejected (E-level) or corrected (W-level) depending on the BAD-BOUNDARY-CHARS and BAD-BOUNDARY-LENGTH configuration directives in the MAIL-FILTER section.