rem: virtual KNHeaders::To* to(bool create=true)                      { KNHeaders::To *p=0; return getHeaderInstance(p, create); }
add: KNHeaders::To* to(bool create=true)                     { if( (!create && t_o.isEmpty()) || (!create && !doMail()) ) return 0; return &t_o; }
context:    	virtual KNHeaders::To* to(bool create=true)                      { KNHeaders::To *p=0; return getHeaderInstance(p, create); }