Constantele de mai jos sunt definite de această extensie și vor fi disponibile doar dacă această extensie a fost compilată în interiorul PHP, sau a fost încărcată dinamic în timpul rulării.
NIL
    (integer)
   OP_DEBUG
    (integer)
   OP_READONLY
    (integer)
   OP_ANONYMOUS
    (integer)
   OP_SHORTCACHE
    (integer)
   OP_SILENT
    (integer)
   OP_PROTOTYPE
    (integer)
   OP_HALFOPEN
    (integer)
   OP_EXPUNGE
    (integer)
   OP_SECURE
    (integer)
   CL_EXPUNGE
    (integer)
   FT_UID
    (integer)
   FT_PEEK
    (integer)
   FT_NOT
    (integer)
   FT_INTERNAL
    (integer)
   FT_PREFETCHTEXT
    (integer)
   ST_UID
    (integer)
   ST_SILENT
    (integer)
   ST_SET
    (integer)
   CP_UID
    (integer)
   CP_MOVE
    (integer)
   SE_UID
    (integer)
   SE_FREE
    (integer)
   SE_NOPREFETCH
    (integer)
   SO_FREE
    (integer)
   SO_NOSERVER
    (integer)
   SA_MESSAGES
    (integer)
   SA_RECENT
    (integer)
   SA_UNSEEN
    (integer)
   SA_UIDNEXT
    (integer)
   SA_UIDVALIDITY
    (integer)
   SA_ALL
    (integer)
   LATT_NOINFERIORS
    (integer)
   LATT_NOSELECT
    (integer)
   LATT_MARKED
    (integer)
   LATT_UNMARKED
    (integer)
   SORTDATE
    (integer)
   SORTARRIVAL
    (integer)
   SORTFROM
    (integer)
   SORTSUBJECT
    (integer)
   SORTTO
    (integer)
   SORTCC
    (integer)
   SORTSIZE
    (integer)
   TYPETEXT
    (integer)
   TYPEMULTIPART
    (integer)
   TYPEMESSAGE
    (integer)
   TYPEAPPLICATION
    (integer)
   TYPEAUDIO
    (integer)
   TYPEIMAGE
    (integer)
   TYPEVIDEO
    (integer)
   TYPEMODEL
    (integer)
   TYPEOTHER
    (integer)
   ENC7BIT
    (integer)
   ENC8BIT
    (integer)
   ENCBINARY
    (integer)
   ENCBASE64
    (integer)
   ENCQUOTEDPRINTABLE
    (integer)
   ENCOTHER
    (integer)
   IMAP_OPENTIMEOUT
    (integer)
   IMAP_READTIMEOUT
    (integer)
   IMAP_WRITETIMEOUT
    (integer)
   IMAP_CLOSETIMEOUT
    (integer)
   LATT_REFERRAL
    (integer)
   LATT_HASCHILDREN
    (integer)
   LATT_HASNOCHILDREN
    (integer)
   IMAP_GC_ELT
    (integer)
   IMAP_GC_ENV
    (integer)
   IMAP_GC_TEXTS
    (integer)