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PHP Manual :: imap_open

imap_num_recent || imap_ping || IMAP Functions || PHP Manual

(PHP 4, PHP 5, PHP 7)

imap_openOpen an IMAP stream to a mailbox


resource imap_open ( string $mailbox , string $username , string $password [, int $options = 0 [, int $n_retries = 0 [, array $params = NULL ]]] )

Opens an IMAP stream to a mailbox.

This function can also be used to open streams to POP3 and NNTP servers, but some functions and features are only available on IMAP servers.



A mailbox name consists of a server and a mailbox path on this server. The special name INBOX stands for the current users personal mailbox. Mailbox names that contain international characters besides those in the printable ASCII space have to be encoded width imap_utf7_encode().

The server part, which is enclosed in '{' and '}', consists of the servers name or ip address, an optional port (prefixed by ':'), and an optional protocol specification (prefixed by '/').

The server part is mandatory in all mailbox parameters.

All names which start with { are remote names, and are in the form "{" remote_system_name [":" port] [flags] "}" [mailbox_name] where:

  • remote_system_name - Internet domain name or bracketed IP address of server.
  • port - optional TCP port number, default is the default port for that service
  • flags - optional flags, see following table.
  • mailbox_name - remote mailbox name, default is INBOX

Optional flags for names
Flag Description
/service=service mailbox access service, default is "imap"
/user=user remote user name for login on the server
/authuser=user remote authentication user; if specified this is the user name whose password is used (e.g. administrator)
/anonymous remote access as anonymous user
/debug record protocol telemetry in application's debug log
/secure do not transmit a plaintext password over the network
/imap, /imap2, /imap2bis, /imap4, /imap4rev1 equivalent to /service=imap
/pop3 equivalent to /service=pop3
/nntp equivalent to /service=nntp
/norsh do not use rsh or ssh to establish a preauthenticated IMAP session
/ssl use the Secure Socket Layer to encrypt the session
/validate-cert validate certificates from TLS/SSL server (this is the default behavior)
/novalidate-cert do not validate certificates from TLS/SSL server, needed if server uses self-signed certificates
/tls force use of start-TLS to encrypt the session, and reject connection to servers that do not support it
/notls do not do start-TLS to encrypt the session, even with servers that support it
/readonly request read-only mailbox open (IMAP only; ignored on NNTP, and an error with SMTP and POP3)


The user name


The password associated with the username


The options are a bit mask with one or more of the following:

  • OP_READONLY - Open mailbox read-only
  • OP_ANONYMOUS - Don't use or update a .newsrc for news (NNTP only)
  • OP_HALFOPEN - For IMAP and NNTP names, open a connection but don't open a mailbox.
  • CL_EXPUNGE - Expunge mailbox automatically upon mailbox close (see also imap_delete() and imap_expunge())
  • OP_DEBUG - Debug protocol negotiations
  • OP_SHORTCACHE - Short (elt-only) caching
  • OP_SILENT - Don't pass up events (internal use)
  • OP_PROTOTYPE - Return driver prototype
  • OP_SECURE - Don't do non-secure authentication


Number of maximum connect attempts


Connection parameters, the following (string) keys maybe used to set one or more connection parameters:

  • DISABLE_AUTHENTICATOR - Disable authentication properties

Return Values

Returns an IMAP stream on success or FALSE on error.


Version Description
5.3.2 params added
5.2.0 n_retries added


Example #1 Different use of imap_open()

// To connect to an IMAP server running on port 143 on the local machine,
// do the following:
$mbox imap_open("{localhost:143}INBOX""user_id""password");

// To connect to a POP3 server on port 110 on the local server, use:
$mbox imap_open ("{localhost:110/pop3}INBOX""user_id""password");

// To connect to an SSL IMAP or POP3 server, add /ssl after the protocol
// specification:
$mbox imap_open ("{localhost:993/imap/ssl}INBOX""user_id""password");

// To connect to an SSL IMAP or POP3 server with a self-signed certificate,
// add /ssl/novalidate-cert after the protocol specification:
$mbox imap_open ("{localhost:995/pop3/ssl/novalidate-cert}""user_id""password");

// To connect to an NNTP server on port 119 on the local server, use:
$nntp imap_open ("{localhost:119/nntp}comp.test""""");
// To connect to a remote server replace "localhost" with the name or the
// IP address of the server you want to connect to.

Example #2 imap_open() example


$folders imap_listmailbox($mbox"{}""*");

if (
$folders == false) {
"Call failed<br />\n";
} else {
    foreach (
$folders as $val) {
$val "<br />\n";

"<h1>Headers in INBOX</h1>\n";
$headers imap_headers($mbox);

if (
$headers == false) {
"Call failed<br />\n";
} else {
    foreach (
$headers as $val) {
$val "<br />\n";


See Also

imap_num_recent || imap_ping || IMAP Functions || PHP Manual
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