if (!p)
if (!p || !p[1])
static int mbox_to_udomain (const char *mbx, char **user, char **domain){  char *p;  *user = NULL;  *domain = NULL;    p = strchr (mbx, '@');  if (!p)    return -1;  *user = safe_calloc((p - mbx + 1), sizeof(mbx[0]));  strfcpy (*user, mbx, (p - mbx + 1));  *domain = safe_strdup(p + 1);  return 0;}