gmail-imap.php

<?php

// Turn off all error reporting
error_reporting(0);

// Configuration
$user = 'your_login';
$password = 'you_password';
$host = 'imap.gmail.com';

// Default data array
$items = array(
	'msg' => array(), 
	'unseen_items' => array()
);

// Open an IMAP stream to a mailbox
$mailbox = imap_open("{" . $host . ":993/imap/ssl}INBOX", $user, $password, OP_READONLY);

if ($mailbox === false) {
	echo 'Error : ' . imap_last_error();
} else {
	// Gets status information about the given mailbox
	$status = imap_status($mailbox, "{" . $host . "}INBOX", SA_ALL);
	if ($status === false) {
		echo 'Error : ' . imap_last_error();
	} else {
		$items['msg']['all'] = $status->messages;
		$items['msg']['unseen'] = $status->unseen;

		// No unseen messages
		if ($status->unseen == 0) {
			echo 'No unseen messages';
		} else {
			// Gets UIDs for unseen messages
			$messages = imap_search($mailbox, 'UNSEEN');

			if ($messages === false) {
				echo 'Error : ' . imap_last_error();
			} else {
				// For each all unseen messages
				foreach($messages as $uid ) {
					// Get header of the message
					$message = imap_headerinfo($mailbox, $uid);

					if ($message) {
						// From message
						$from = $message->from[0];
						$from_addres = $from->mailbox . "@" . $from->host;

						// Subject
						$subject = isset($message->subject)
							? imap_utf8($message->subject) : 'No subject';

						// Re-format date
						$date = date("Y-m-d H:i", strtotime($message->date));

						// Add to data array
						$items['msg']['unseen_items'][] = array(
							$uid, $from_addres, $date, $subject
						);
					}
				}
			}
		}
	}

	// Close an IMAP stream
	imap_close($mailbox);
}

// Show messages from data array
echo '<pre>' . print_r($items, true) . '</pre>';

You should use App Passwords in order to access the emails https://support.google.com/accounts/answer/185833

@miljushm Thanks. This gist was created 7 years ago. Only for my tests and fun. I don't want to change anything.

You don't need to change anything because it works well, I just left the comment for the future in case somebody like @motsmanish has the issue with the login to Gmail (it now requires App Passwords) ;)