(PHP 5 >= 5.3.6, PHP 7)
imap_fetchmime — Fetch MIME headers for a particular section of the message
$imap_stream
   , int $msg_number
   , string $section
   [, int $options = 0
  ] ) : stringFetch the MIME headers of a particular section of the body of the specified messages.
imap_stream由 imap_open() 返回的 IMAP 流。
msg_numberThe message number
sectionThe part number. It is a string of integers delimited by period which index into a body part list as per the IMAP4 specification
optionsA bitmask with one or more of the following:
FT_UID - The msg_number is a UID
         
        FT_PEEK - Do not set the \Seen flag if
          not already set
         
        FT_INTERNAL - The return string is in
          internal format, will not canonicalize to CRLF.
         
        Returns the MIME headers of a particular section of the body of the specified messages as a text string.