diff --git a/lib/imap.php b/lib/imap.php
index fee0813..37926b1 100644
--- a/lib/imap.php
+++ b/lib/imap.php
@@ -86,9 +86,8 @@ class OC_User_IMAP extends \OCA\user_external\Base {
 
 		$params = ["port"=>$this->port, "timeout"=>10];
 
-		if ($this->sslmode !== null){
-			$params["ssl_mode"] = $this->sslmode;
-		}
+		$params["ssl_mode"] = $this->sslmode ? $this->sslmode : null;
+		$params["force_caps"] = false;
 		$canconnect = $rcube->connect(
 					$this->mailbox,
 					$username,
diff --git a/lib/imap/imap_rcube.php b/lib/imap/imap_rcube.php
index f5b5b79..ceec1e5 100644
--- a/lib/imap/imap_rcube.php
+++ b/lib/imap/imap_rcube.php
@@ -146,7 +146,7 @@ class imap_rcube
         $res = 0;
         if ($parts = preg_split('/(\{[0-9]+\}\r\n)/m', $string, -1, PREG_SPLIT_DELIM_CAPTURE)) {
             for ($i=0, $cnt=count($parts); $i<$cnt; $i++) {
-                if (preg_match('/^\{([0-9]+)\}\r\n$/', $parts[$i+1], $matches)) {
+                if (isset($parts[$i+1]) && preg_match('/^\{([0-9]+)\}\r\n$/', $parts[$i+1], $matches)) {
                     // LITERAL+ support
                     if ($this->prefs['literal+']) {
                         $parts[$i+1] = sprintf("{%d+}\r\n", $matches[1]);