Typo: an valid -> a valid.

en_US/howto/letsencrypt.md

@@ -3,7 +3,7 @@
 [TOC]
 
 iRedMail generates a self-signed SSL certificate during installation, it's
-strongly recommended to use an valid ssl cert.
+strongly recommended to use a valid ssl cert.
 
 You can either request free cert, or buy one from ssl cert vendors. In this
 tutorial, we will show you how to request a free cert for host name

en_US/iredadmin/2-iredadmin-pro.domain.ownership.verification.md

@@ -9,7 +9,7 @@ normal domain admin permission to create new mail domains. All new domains
 added by normal domain admin require domain ownership verification by deafult,
 to ensure:
 
-* the newly added mail domain name is an valid domain name on internet
+* the newly added mail domain name is a valid domain name on internet
 * the domain admin have the required privileges in the domain to manage the
   email services
 

html/iredadmin-pro.domain.ownership.verification.html

@@ -32,7 +32,7 @@ normal domain admin permission to create new mail domains. All new domains
 added by normal domain admin require domain ownership verification by deafult,
 to ensure:</p>
 <ul>
-<li>the newly added mail domain name is an valid domain name on internet</li>
+<li>the newly added mail domain name is a valid domain name on internet</li>
 <li>the domain admin have the required privileges in the domain to manage the
   email services</li>
 </ul>

html/letsencrypt.html

@@ -54,7 +54,7 @@
 </ul>
 </div>
 <p>iRedMail generates a self-signed SSL certificate during installation, it's
-strongly recommended to use an valid ssl cert.</p>
+strongly recommended to use a valid ssl cert.</p>
 <p>You can either request free cert, or buy one from ssl cert vendors. In this
 tutorial, we will show you how to request a free cert for host name
 <code>mail.mydomain.com</code> from <strong><a href="https://letsencrypt.org">Let's Encrypt</a></strong>, and ssl