diff --git a/en_US/upgrade/0-upgrade.iredmail.0.9.9-1.0.md b/en_US/upgrade/0-upgrade.iredmail.0.9.9-1.0.md
index 1ba2885b..de9a720c 100644
--- a/en_US/upgrade/0-upgrade.iredmail.0.9.9-1.0.md
+++ b/en_US/upgrade/0-upgrade.iredmail.0.9.9-1.0.md
@@ -87,8 +87,8 @@ DNS records (especially your internal mail domains used in LAN). Please follow
 steps below to fix it.
 
 * Open file `/etc/postfix/main.cf` (Linux/OpenBSD) or
-`/usr/local/etc/postfix/main.cf` (FreeBSD), find parameter
-`smtpd_sender_restrictions` like below:
+  `/usr/local/etc/postfix/main.cf` (FreeBSD), find parameter
+  `smtpd_sender_restrictions` like below:
 
 ```
 smtpd_sender_restrictions =
@@ -109,6 +109,28 @@ smtpd_sender_restrictions =
 
 * Reloading or restarting Postfix service is required.
 
+### Fixed: fix improper HELO rule which blocks new Facebook servers
+
+Facebook has some new servers which uses `<ip>.mail-mail.facebook.com` as
+HELO identities, this is blocked by the default HELO rules configured by
+iRedMail-0.9.9 and earlier releases. Please fix it with EITHER step described
+below, but solution 1 is the recommended.
+
+1. Prepend line below in `/etc/postfix/helo_access.pcre` (Linux/OpenBSD) and
+  `/usr/local/etc/postfix/helo_access.pcre` (FreeBSD):
+
+```
+/^\d{1,3}-\d{1,3}-\d{1,3}-\d{1,3}\.mail-mail\.facebook\.com$/ DUNNO
+```
+
+2. Or, find line below in `helo_access.pcre` and remove it.
+
+```
+/(\d{1,3}[\.-]\d{1,3}[\.-]\d{1,3}[\.-]\d{1,3})/ REJECT ACCESS DENIED. Your email was rejected because the sending mail server appears to be on a dynamic IP address that should not be doing direct mail delivery
+```
+
+Reloading or restarting Postfix service is required.
+
 ### Fixed: Incorrect SSL CA file path in Postfix on FreeBSD and OpenBSD
 
 !!! attention
diff --git a/html/upgrade.iredmail.0.9.9-1.0.html b/html/upgrade.iredmail.0.9.9-1.0.html
index 33b04d26..9eae0600 100644
--- a/html/upgrade.iredmail.0.9.9-1.0.html
+++ b/html/upgrade.iredmail.0.9.9-1.0.html
@@ -28,6 +28,7 @@
 <li><a href="#upgrade-roundcube-webmail-to-the-latest-stable-release">Upgrade Roundcube webmail to the latest stable release</a></li>
 <li><a href="#upgrade-netdata-to-the-latest-stable-release-1171">Upgrade netdata to the latest stable release (1.17.1)</a></li>
 <li><a href="#fixed-improper-order-of-postfix-smtpd_sender_restriction-rules">Fixed: improper order of Postfix smtpd_sender_restriction rules</a></li>
+<li><a href="#fixed-fix-improper-helo-rule-which-blocks-new-facebook-servers">Fixed: fix improper HELO rule which blocks new Facebook servers</a></li>
 <li><a href="#fixed-incorrect-ssl-ca-file-path-in-postfix-on-freebsd-and-openbsd">Fixed: Incorrect SSL CA file path in Postfix on FreeBSD and OpenBSD</a></li>
 <li><a href="#fail2ban-slightly-loose-filter-rule-for-postfix">Fail2ban: slightly loose filter rule for postfix</a></li>
 </ul>
@@ -133,8 +134,8 @@ DNS records (especially your internal mail domains used in LAN). Please follow
 steps below to fix it.</p>
 <ul>
 <li>Open file <code>/etc/postfix/main.cf</code> (Linux/OpenBSD) or
-<code>/usr/local/etc/postfix/main.cf</code> (FreeBSD), find parameter
-<code>smtpd_sender_restrictions</code> like below:</li>
+  <code>/usr/local/etc/postfix/main.cf</code> (FreeBSD), find parameter
+  <code>smtpd_sender_restrictions</code> like below:</li>
 </ul>
 <pre><code>smtpd_sender_restrictions =
     reject_unknown_sender_domain
@@ -155,6 +156,25 @@ steps below to fix it.</p>
 <ul>
 <li>Reloading or restarting Postfix service is required.</li>
 </ul>
+<h3 id="fixed-fix-improper-helo-rule-which-blocks-new-facebook-servers">Fixed: fix improper HELO rule which blocks new Facebook servers</h3>
+<p>Facebook has some new servers which uses <code>&lt;ip&gt;.mail-mail.facebook.com</code> as
+HELO identities, this is blocked by the default HELO rules configured by
+iRedMail-0.9.9 and earlier releases. Please fix it with EITHER step described
+below, but solution 1 is the recommended.</p>
+<ol>
+<li>Prepend line below in <code>/etc/postfix/helo_access.pcre</code> (Linux/OpenBSD) and
+  <code>/usr/local/etc/postfix/helo_access.pcre</code> (FreeBSD):</li>
+</ol>
+<pre><code>/^\d{1,3}-\d{1,3}-\d{1,3}-\d{1,3}\.mail-mail\.facebook\.com$/ DUNNO
+</code></pre>
+
+<ol>
+<li>Or, find line below in <code>helo_access.pcre</code> and remove it.</li>
+</ol>
+<pre><code>/(\d{1,3}[\.-]\d{1,3}[\.-]\d{1,3}[\.-]\d{1,3})/ REJECT ACCESS DENIED. Your email was rejected because the sending mail server appears to be on a dynamic IP address that should not be doing direct mail delivery
+</code></pre>
+
+<p>Reloading or restarting Postfix service is required.</p>
 <h3 id="fixed-incorrect-ssl-ca-file-path-in-postfix-on-freebsd-and-openbsd">Fixed: Incorrect SSL CA file path in Postfix on FreeBSD and OpenBSD</h3>
 <div class="admonition attention">
 <p class="admonition-title">Attention</p>