Horde_Imap_Client

An IMAP4rev1 / IMAP4rev2 (RFC 3501 / RFC 9051) and POP3 (RFC 1939) client library for PHP.

The package ships two codebases side by side:

• src/ (namespace Horde\Imap\Client): the modern, PSR-4, PHP 8.2+ rewrite. Small final classes and immutable value objects, built on Horde\Socket\Client and Horde\Sasl. This is the recommended API for new code.
• lib/ (Horde_Imap_Client_*): the legacy PSR-0 engine, retained for backward compatibility. Functional but not actively developed.

Modern usage

use Horde\Imap\Client\ConnectionConfig;
use Horde\Imap\Client\ImapClient;
use Horde\Imap\Client\ImapFetchQuery;
use Horde\Imap\Client\OpenMode;
use Horde\Imap\Client\SecureMode;
use Horde\Sasl\Credentials\PasswordCredentials;
use Horde\Sasl\Credentials\PlainSecret;

$client = new ImapClient(
    new ConnectionConfig(hostspec: 'imap.example.com', port: 993, secure: SecureMode::Ssl),
    new PasswordCredentials('alice', new PlainSecret('secret')),
);

$client->login();
$client->openMailbox('INBOX', OpenMode::Readonly);

$query = (new ImapFetchQuery())->envelope()->flags();
foreach ($client->fetch('INBOX', $client->getIdsOb('1:*'), $query) as $uid => $msg) {
    echo $uid . ': ' . $msg->getEnvelope()->subject . "\n";
}

$client->logout();

ImapClient implements ImapProtocol (and MailboxProtocol), plus the optional ImapAclAware, ImapQuotaAware and ImapMetadataAware extension interfaces. Pop3Client implements MailboxProtocol.

Message caching is opt-in: pass an ImapCacheStore (backed by any PSR-16 cache) as the fifth ImapClient constructor argument and it is used transparently across fetch, store and expunge.

Supported extensions

STARTTLS, SASL (via Horde\Sasl), CAPABILITY/ENABLE, IMAP4rev2, UTF8=ACCEPT, UIDPLUS, MOVE, CONDSTORE/QRESYNC, ESEARCH, SORT/ESORT, THREAD, LIST-EXTENDED, LIST-STATUS, NAMESPACE, ACL, QUOTA, METADATA, MULTIAPPEND, CATENATE, BINARY and SEARCH=FUZZY.

Documentation

• doc/UPGRADING.md: migrating from the legacy lib/ API to the modern src/ clients, with a class-mapping table and before/after examples.
• doc/examples/imapclient.php: a runnable, read-only IMAP demonstration (capabilities, namespaces, mailbox list, status, fetch, search).
• doc/examples/pop3client.php: the equivalent POP3 demonstration.
• doc/POP3CAPABILITIES.md: what the POP3 client implements, what it deliberately does not and a server-compatibility matrix.

License

LGPL 2.1. See the enclosed LICENSE file.