To increase security, you can encrypt the communication between Jira and your mail server if your mail server supports SSL. There are two steps involved in enabling SSL over SMTP in Jira:

• The first step is to import your mail server's SSL certificate into Java's trust store. You can do this with Java's keytool utility. On a Windows machine, run the following command in Command Prompt:

Keytool -import -alias mail.yourcompany.com -keystore    $JAVA_HOME/jre/lib/security/cacerts -file yourcertificate

• The second step is to configure your application server to use SSL for mail communication. The following declaration is for Apache Tomcat, which is used by Jira standalone. We use the same configuration file and only need to add two additional parameters:

<Resource name="mail/JiraMailServer" 
  auth="Container" 
  type="javax.mail.Session" 
  mail.smtp.host="mail.server.host" 
  mail.smtp.port="25" 
  mail.transport.protocol="smtp" 
  mail.smtp.auth="true" 
  mail.smtp.user="username" 
  password="password" 
  mail.smtp.atarttls.enabled="true" 
mail.smtp.socketFactory.class="javax.net.ssl.SSLSocketFactory" 
/> 

Once you have imported your certificate and configured your mail server, you will have to restart Jira.