fix long imap login delay on mailboxes with many folders

Signed-off-by: Malte Langermann <malte@langermann.net>

Author: gagarinlg

lib/imap.php

@@ -95,6 +95,7 @@ public function checkPassword($uid, $password) {
 		curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
 		curl_setopt($ch, CURLOPT_USERPWD, $username.":".$password);
 		curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
+		curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'CAPABILITY');
 
 		$canconnect = curl_exec($ch);