static inline unsigned is_cached_header(const char *hdr)
{
    size_t len;
    struct mailbox_header_cache *thdr;

    len = strlen(hdr);
    if (len >= MAX_CACHED_HEADER_SIZE)
        return BIT32_MAX;

    thdr = mailbox_header_cache_lookup(hdr, len);

    if (thdr)
        return thdr->min_cache_version;

    /* Don't Cache X- headers unless explicitly configured to*/
    if (((hdr[0] == 'x') || (hdr[0] == 'X')) &&
        (hdr[1] == '-')) return BIT32_MAX;

    /* Everything else we cache in version 1 */
    return 1;
}
static inline unsigned is_cached_header(const char *hdr)
{
    size_t len;
    struct mailbox_header_cache *thdr;

    len = strlen(hdr);
    if (len >= MAX_CACHED_HEADER_SIZE)
        return BIT32_MAX;

    thdr = mailbox_header_cache_lookup(hdr, len);

    if (thdr)
        return thdr->min_cache_version;

     
    if (((hdr[0] == 'x') || (hdr[0] == 'X')) &&
        (hdr[1] == '-')) return BIT32_MAX;

     
    return 1;
}