前提：
公司同仁說一月份還可以收到對方的信件，這幾天卻不行

先行處理方式：

1. 請對方寄到公司同仁的私人信箱沒問題
2. 檢查防火牆(FortiGate 200D)郵件訊息，沒有收到任何異常訊息
   應該是還沒到公司就被擋掉了
3. 請對方提供郵件錯誤訊息，如下
   XXX@yiehmau.com.tw
   host mailfilter.yiehmau.com.tw [210.71.187.212]
   SMTP error from remote mail server after RCPT TO:XXX@yiehmau.com.tw:
   550 Your access IP (188.40.30.17) to submit messages to this e-mail system has been rejected.

Return-path: XXX@prohrominox.com
Received: from [88.198.220.130] (helo=sslproxy01.your-server.de)
by www308.your-server.de with esmtpsa
(TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256)
(Exim 4.85_2)
(envelope-from XXX@prohrominox.com)
id 1exq9t-0008PJ-Hn
for XXX@yiehmau.com.tw; Mon, 19 Mar 2018 09:28:45 +0100
Received: from [178.222.38.2] (helo=DESKTOP3M706IG)
by sslproxy01.your-server.de with esmtpsa
(TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256)
(Exim 4.84_2)
(envelope-from XXX@prohrominox.com)
id 1exq9q-00039b-H3
for XXX@yiehmau.com.tw; Mon, 19 Mar 2018 09:28:45 +0100
Message-ID: FF39D14A981B437A9FD33B0B167F0A8E@DESKTOP3M706IG
From: "XXX Marinkovic / PROHROM" XXX@prohrominox.com
To: "XXX XXX" XXX@yiehmau.com.tw
References: 006b01d3bf5a$bc759260$3560b720$@yiehmau.com.tw
In-Reply-To: 006b01d3bf5a$bc759260$3560b720$@yiehmau.com.tw
Subject: Re: yieh mau test mail
Date: Mon, 19 Mar 2018 09:28:39 +0100
MIME-Version: 1.0
Content-Type: multipart/related;
type="multipart/alternative";
boundary="----=_NextPart_000_0102_01D3BF64.AADCFAC0"
X-Priority: 3
X-MSMail-Priority: Normal
Importance: Normal
X-Mailer: Microsoft Windows Live Mail 16.4.3503.728
X-MimeOLE: Produced By Microsoft MimeOLE V16.4.3503.728
X-Authenticated-Sender: XXX@prohrominox.com
X-Virus-Scanned: Clear (ClamAV 0.99.3/24399/Mon Mar 19 03:39:44 2018)

有爬了文，但是還是找不出解決方式...
請問要如何處裡？感謝