1 elements attributes attributes elements elements attributes allow reject attach attachPlaceHolder unwrap 5.1 of RFC 2045 allows <any (US-ASCII) CHAR except SPACE, CTLs, or tspecials>, where tspecials := "(" / ")" / "<" / ">" / "@" / "," / ";" / ":" / "\" / <"> "/" / "[" / "]" / "?" / "=" \s*[0-9A-Za-z!#$%&'\*\+\-\.\^_`\{\|\}~]*\\[0-9A-Za-z!#$%&'\*\+\-\.\^_`\{\|\}~]*\s* \s*(/\s*)?\i\c*(\s*/\s*\i\c*)*\s*(\|\s*(/\s*)?\i\c*(\s*/\s*\i\c*)*\s*)*