PHP Manual: Subscribe to a mailbox

bool imap_subscribe(IMAP\Connection $imap, string $mailbox)

Subscribe to a new mailbox.

imap: An IMAP\Connection instance.
mailbox: The mailbox name, see imap_open for more information

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

Returns true on success or false on failure.

Version	Description
8.1.0	The `imap` parameter expects an IMAP\Connection instance now; previously, a valid `imap` resource was expected.

imap_subscribe