Re-initialize message idx before saving bounced message header.

src/sbbs3/mailsrvr.c

@@ -3334,6 +3334,7 @@ BOOL bounce(smb_t* smb, smbmsg_t* msg, char* err, BOOL immediate)
 	smb_hfield_str(&newmsg, SMB_COMMENT, err);
 	smb_hfield_str(&newmsg, SMB_COMMENT, "\r\nOriginal message text follows:\r\n");
 
+	smb_init_idx(smb,&newmsg);
 	if((i=smb_addmsghdr(smb,&newmsg,SMB_SELFPACK))!=SMB_SUCCESS)
 		lprintf(LOG_ERR,"0000 !BOUNCE ERROR %d (%s) adding message header"
 			,i,smb->last_error);