Enable SMTP authentication for Outlook 2010-2016

Applies to: Plesk-Hosted email

    <h3>Enabling SMTP authentication</h3>

    <ol>
      <li>Open <b>Outlook</b></li>
      <li>Click on the <b>Files</b> menu tab and select <b>Account Settings</b>. The <b>
        Account Settings</b> box appears.</li>

      <li>Verify that the <b>E-mail</b> tab is selected. Your email account appears, it might be labeled with your name of domain.</li>
      <li>Click on the account to highlight it, and click on the <b>Change</b> icon above it.
        The Internet E-mail Settings appear.</li>

      <li>Under the Server Information section, in the box marked <b>Outgoing mail server (SMTP)</b> check that it is set to your Plesk server name (psaXXX.his.com) or Zimbra server name (xxx.his.com)</li>
        <li>Click the button <b>More Settings...</b> in the lower right-hand corner. 
        The Internet Email Settings box appears.</li>
        <li>Click on the tab <b>Outgoing Server</b>.</li>

        <li>Click the check box <b>My outgoing server (SMTP) requires authentication</b>,
        and verify that the box <b>Use same settings as my incoming mail server</b>
        is selected.</li>
      <li>Click the <b>Advanced</b> tab</li>
      <li>Change the Outgoing server (SMTP) from 25 to  <b>465</b> *. Click OK. </li>

        <li>Make Sure Encryption is set  SSL/TLS for port  465 </li>
        <li>Click <b>OK</b> to close the Internet Email Settings box. </li>
         <li>Click the <b>Next</b> button to test your settings.<br>
        Click the <b>Finish</b> button to close the Internet E-mail Settings box. <br>
        Click the <b>Close</b> button to close the <b>Account Settings</b> 
        box.&nbsp; SMTP authentication has now been
        enabled.</li>
    </ol>

* Note: An increasing number of cable and DSL providers (Comcast, Cox, Roadrunner, Verizon, etc...) are blocking the default SMTP port 25 except for their own mail servers. This is being done to help reduce the amount of spam sent from infected customer PCs.
Symptoms: you get an error sending mail, saying "could not connect to ".
Solution:In order to send email through your HIS mail server from your cable/DSL account you will need to use use port 465 with SSL.

Source: https://support.microsoft.com/en-us/kb/2758902