How to resolve outlook error code 18

Microsoft Outlook is one of the best applications in Microsoft Office suit that helps you to send or receive email messages offline. But sometimes like other applications Outlook also gets some error message like Outlook error code 18 on the screen of your computer. It is very important for you to use the Outlook account with a great care. The error generally doesn’t create a big issue but if it is not resolved soon then it may be a cause of severe data loss in the system. You can go through some manual methods or you can also use Outlook PST Repair Tool to remove the problem automatically.

Compatible with Outlook 2000, 2002, 2003, 2007, 2010, 2013 and supports Windows 8, 7 (32-bit/64-bit), Vista (32-bit/64-bit ), 2003, XP, 2000, NT4 (SP6).

Symptoms –

You can get the Outlook error message 18 just like;

“There is a problem with the proxy server’s security certificate. The security certificate is not from a trusts certifying authority.” “Outlook is unable to connect to the proxy server (Error code 18)”

Causes –

The main reasons behind the prompting of Outlook error code 18 are the corrupt PST files, damaged Outlook application, firewall settings, antivirus software. Beside these the error code 18 also comes to your computer if you are using remote procedure call (RPC) connection or secure HTTP (HTTPS) connection, if the certification authority is not trusted.

Solution –

Go through the following manual method to get rid of outlook error code 18:

  1. When you get prompting of certificate dialog box then click on install certificate and click on next.
  2. Select “Place all certificate in the following store” check box.
  3. Click on browse.
  4. Go to Trusted Root Certificate Authorities and click on OK button.
  5. Click on next and then click on finish.

At the end of the process you will find that you are now able to send or receive mails or messages and prompting of Outlook error code 18 is also removed from the computer. But in case if you cannot fix the problem using manual method then you should download and install Outlook PST Repair Tool to fix the issue automatically.

Compatible with Outlook 2000, 2002, 2003, 2007, 2010, 2013 and supports Windows 8, 7 (32-bit/64-bit), Vista (32-bit/64-bit ), 2003, XP, 2000, NT4 (SP6).

Outlook PST Repair Tool will also help in trusting the certificate authorities and fix the entire Outlook issue automatically. With the help of this tool you can also repair the damaged Outlook application and PST files. This tool will also help you to enhance the performance of the application as well as the computer.


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