Issue Some mails are delayed

[Jordyboutier]

Hi,

I have successfully set-up Plesk on my VPS. I am using it as a webserver and mailserver. Some of my e-mails are delivered with some delay. I am using Roundcube as webmail client. See here on of those mailheaders:

Authentication-Results: jordyboutier.nl;
dkim=pass (good signature) header.i=010101581afd6919-6dd78432-7713-4e5c-8c72-f81b0a8aa7a8-000000@us-west-2.amazonses.com
Return-Path: <010101581afd6919-6dd78432-7713-4e5c-8c72-f81b0a8aa7a8-000000@us-west-2.amazonses.com>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on jordyboutier.nl
X-Spam-Level:
X-Spam-Status: No, score=-1.6 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,HTML_MESSAGE,MIME_HTML_ONLY,
RCVD_IN_DNSWL_BLOCKED,RP_MATCHES_RCVD,URIBL_BLOCKED autolearn=unavailable
autolearn_force=no version=3.4.0
X-Original-To: info@jordyboutier.nl
Delivered-To: info@jordyboutier.nl
Received: from a27-30.smtp-out.us-west-2.amazonses.com (a27-30.smtp-out.us-west-2.amazonses.com [54.240.27.30])
by jordyboutier.nl (Postfix) with ESMTPS id 61E3B108A6C2
for <info@jordyboutier.nl>; Mon, 31 Oct 2016 16:54:01 +0100 (CET)
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple;
s=sod6d74xbo3sghwjb4ezldllbzg2jtpw; d=holyticket.com; t=1477921565;
h=From:Toate:Message-ID:Subject:MIME-Version:Content-Type:Content-Transfer-Encoding;
bh=W2L5kf/DZKM+mnWFDjrREEBVSqeWhum26Gyc5iiKnK4=;
b=FN02v2pEisVzxbWxM6oUozuulLqqDjD+I6/s6tUrUmbLmpMA2fjaYiplKSZbPnRf
Y0NJ7ZHEr+R+MvKEOde/teUaCBDI2uSjdrChG5fzUC0I4BqNdkaXvUefs3qNvmH+D1+
p7mpvyzCxv3pE2yYv6Okua23jUC4BbibH37GfmvE=
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple;
s=gdwg2y3kokkkj5a55z2ilkup5wp5hhxx; d=amazonses.com; t=1477921565;
h=From:Toate:Message-ID:Subject:MIME-Version:Content-Type:Content-Transfer-Encoding:Feedback-ID;
bh=W2L5kf/DZKM+mnWFDjrREEBVSqeWhum26Gyc5iiKnK4=;
b=hJ6Qe/VXt8CIpUIwrLUGR8ODIGR8+SecgC+vOUEJOlTAvlTEsvWA3Eq+aNopaUFQ
GdKu+XPkN/YR23Zkc8Q+b260H0GQVVe7WUdTBZBuf8eUfu7mIoFrTxL0X7Gm9q9bbg6
LVNU9MycHBfpE3e+NiaADHKx1TMkvdOrra01VIGE=
From: "HolyTicket.com" <contact@holyticket.com>
To: info@jordyboutier.nl
X-Mailer: CakePHP Email
Date: Mon, 31 Oct 2016 13:46:05 +0000
Message-ID: <010101581afd6919-6dd78432-7713-4e5c-8c72-f81b0a8aa7a8-000000@us-west-2.amazonses.com>
Subject: Gebr. de Nobel: Je ticket(s) voor MEMPHIS MANIACS
MIME-Version: 1.0
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-SES-Outgoing: 2016.10.31-54.240.27.30
Feedback-ID: 1.us-west-2.ZrBXXbWAceaqOmArbVjl4K1w4P+Rk9XLdEeWLQlp9SU=:AmazonSES

Does anyone have an idea how to fix this?

Regards,
Jordy