diff --git a/en_US/howto/2-sign.dkim.signature.for.new.domain.md b/en_US/howto/2-sign.dkim.signature.for.new.domain.md
index cfda0497..2cc89efa 100644
--- a/en_US/howto/2-sign.dkim.signature.for.new.domain.md
+++ b/en_US/howto/2-sign.dkim.signature.for.new.domain.md
@@ -62,12 +62,15 @@ tutorial to [add DKIM DNS record](setup.dns.html#dkim-record-for-your-mail-domai
 # amavisd-new genrsa /var/lib/dkim/new_domain.com.pem 2048
 ```
 
-Note: if you're running CentOS, you may need to specify its config file on
-command line. For example:
+> * if you're running CentOS, you may need to specify its config file on
+>   command line. For example:
+> 
+> `# amavisd -c /etc/amavisd/amavisd.conf genrsa /var/lib/dkim/new_domain.com.pem 2048`
 
-```
-# amavisd -c /etc/amavisd/amavisd.conf genrsa /var/lib/dkim/new_domain.com.pem 2048
-```
+> * Some DNS provider doesn't support long value for TXT type DNS record, you
+>   need to create a shorter key with key length `1024`. For example:
+> 
+> `# amavisd-new genrsa /var/lib/dkim/new_domain.com.pem 1024`
 
 * Find below setting in Amavisd config file `amavisd.conf`:
 
diff --git a/en_US/installation/0-setup.dns.md b/en_US/installation/0-setup.dns.md
index a0e1a1e5..3a19f050 100644
--- a/en_US/installation/0-setup.dns.md
+++ b/en_US/installation/0-setup.dns.md
@@ -241,6 +241,10 @@ If it shows `pass`, it works.
 __Note__: If you use DNS service provided by ISP, new DNS record might take
 some hours to be available.
 
+If you want to re-generate DKIM key, or need to generate one for new mail
+domain, please check our another tutorial:
+[Sign DKIM signature on outgoing emails for new mail domain](./sign.dkim.signature.for.new.domain.html).
+
 ## References
 
 * [http://en.wikipedia.org/wiki/MX_record](http://en.wikipedia.org/wiki/MX_record)
diff --git a/html/setup.dns.html b/html/setup.dns.html
index 83ff31d2..8770c4a4 100644
--- a/html/setup.dns.html
+++ b/html/setup.dns.html
@@ -243,6 +243,9 @@ TESTING: dkim._domainkey.mydomain.com       => pass
 <p>If it shows <code>pass</code>, it works.</p>
 <p><strong>Note</strong>: If you use DNS service provided by ISP, new DNS record might take
 some hours to be available.</p>
+<p>If you want to re-generate DKIM key, or need to generate one for new mail
+domain, please check our another tutorial:
+<a href="./sign.dkim.signature.for.new.domain.html">Sign DKIM signature on outgoing emails for new mail domain</a>.</p>
 <h2 id="references">References</h2>
 <ul>
 <li><a href="http://en.wikipedia.org/wiki/MX_record">http://en.wikipedia.org/wiki/MX_record</a></li>
diff --git a/html/sign.dkim.signature.for.new.domain.html b/html/sign.dkim.signature.for.new.domain.html
index fdbc17b7..b7c630dd 100644
--- a/html/sign.dkim.signature.for.new.domain.html
+++ b/html/sign.dkim.signature.for.new.domain.html
@@ -74,11 +74,18 @@ tutorial to <a href="setup.dns.html#dkim-record-for-your-mail-domain-name">add D
 <pre><code class="shell"># amavisd-new genrsa /var/lib/dkim/new_domain.com.pem 2048
 </code></pre>
 
-<p>Note: if you're running CentOS, you may need to specify its config file on
-command line. For example:</p>
-<pre><code># amavisd -c /etc/amavisd/amavisd.conf genrsa /var/lib/dkim/new_domain.com.pem 2048
-</code></pre>
-
+<blockquote>
+<ul>
+<li>if you're running CentOS, you may need to specify its config file on
+  command line. For example:</li>
+</ul>
+<p><code># amavisd -c /etc/amavisd/amavisd.conf genrsa /var/lib/dkim/new_domain.com.pem 2048</code></p>
+<ul>
+<li>Some DNS provider doesn't support long value for TXT type DNS record, you
+  need to create a shorter key with key length <code>1024</code>. For example:</li>
+</ul>
+<p><code># amavisd-new genrsa /var/lib/dkim/new_domain.com.pem 1024</code></p>
+</blockquote>
 <ul>
 <li>Find below setting in Amavisd config file <code>amavisd.conf</code>:</li>
 </ul>