PHP 4, PHP 5, PHP 7, PHP 8
imap_open - Open an IMAP stream to a mailbox
Code Examples

     [int$flags = 0],
     [int$retries = 0],
     [array$options = []]
): IMAP\Connection|false

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 with imap_utf7_encode.


Passing untrusted data to this parameter is insecure, unless imap.enable_insecure_rsh is disabled.

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 user


The flags 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\Connection instance on success, or false on failure.


Version Description
8.1.0 Returns an IMAP\Connection instance now; previously, a resource was returned.

Related Functions

Example of imap_open

Show all examples for imap_open

PHP Version:

Function imap_open:

IMAP, POP3 and NNTP Functions

Most used PHP functions