The “Server you are connected to is using a security certificate that cannot be verified” error message is usually caused by an issue with the SSL/TLS certificate used by the website or email server you are trying to connect to. Here are some common causes of this error:
- Expired or invalid SSL/TLS certificate: If the SSL/TLS certificate used by the server has expired, or if it is not properly configured or has been revoked, it will not be able to establish a secure connection, causing the “cannot be verified” error message.
- Mismatched server name: If the server name on the SSL/TLS certificate does not match the server name of the website or email server you are trying to connect to, your browser or email client will not be able to verify the certificate and will display the error message.
- Outdated browser or email client: Older versions of web browsers and email clients may not support the latest SSL/TLS encryption standards, which can cause certificate verification issues.
- Antivirus or firewall interference: Some antivirus and firewall programs can interfere with SSL/TLS certificate verification, causing the “cannot be verified” error message.
- Incorrect system clock: SSL/TLS certificates are time-sensitive, and an incorrect system clock on your computer can cause certificate verification issues.
In summary, there are several possible causes of the “Server you are connected to is using a security certificate that cannot be verified” error message. By addressing the above issues, you may be able to fix the issue and establish a secure connection.
How to Fix The Server You Are Connected to is Using a Security Certificate that Cannot be Verified Error
1. Match Certificate Name
As given in the causes leading to the security certificate error in Outlook, one of the main reasons behind it is the wrong hostname. Therefore, you must ensure that the certificate name is matched. To check it, you can follow the steps stated below:
1. On receiving the Outlook error message on your screen, choose to click on View Certificate… option.
2. Next, click on Issued to Name to ensure that the name there is the same as the name of the mail server.
3. If the name is not the same, change the name and try connecting again.
4. Once done, re-open Outlook and check if the error message is resolved.
2. Use Hosting Domain Name
In case you were unable to resolve the Outlook security alert certificate keeps popping up by matching the certificate name, you can try using the domain name of your hosting as the mail server.
- A large number of domains are hosted by hosting providers.
- The same server for various domains is provided in case of shared hosting.
- If the hosting company does not renew the SSL certificate for every domain, a security error can arise.
- Therefore, you must use the domain name of your hosting company instead of the domain name of the mail server.
- For instance, you can use mail.yourhostingdomain.com instead of using mail.yourdomain.com.
Also Read: How to Recover Deleted Draft in Outlook 365
3. Adjust Date and Time in Windows
The next method to resolve the server you are connected to is using a security certificate that cannot be verified error is by adjusting the date and time settings on your Windows device. Sometimes, the date and time settings of your Windows system can change automatically, and fixing them can help you resolve this error easily. Read our guide on 4 Ways to Change Date and Time in Windows 10 to attempt this method.
4. Clear Internet Cache and History
You can also try clearing the internet cache and history of the browser you are using. Sometimes, due to a corrupt cache and history of your internet browser, you might encounter the server you are connected to is using a certificate that cannot be verified error. Therefore, you must clear your internet cache, and to do so, you can check our guide on How to Clear Cache and Cookies in Google Chrome.
5. Add Non-SSL Ports
Due to blocked ports in places like colleges and universities, you might face issues in connecting to your mail server resulting in Outlook security alert certificate keeps popping up. Usually, the servers blocked are POP 995, SMTP 465, and IMAP 993. In this case, you can use non-SSL ports as they are not blocked. While these non-SSL ports are at risk of data theft, they also have some security parameters. You can use the following non-SSL ports to resolve the mentioned error:
- POP Port: 110
- IMAP Port: 143
- SMTP Port: 587
Also Read: 11 Solutions to Fix Outlook Error This Item Cannot Be Displayed in Reading Pane
6. Change Outlook SMTP Port
The last method to resolve the server you are connected to is using a security certificate that cannot be verified error is to change the Outlook SMTP port. SMTP port 25 is blocked by many ISPs due to spamming. In case your ISP has also blocked this port, you can change the SMTP port to 26 with the help of the steps mentioned below:
1. Launch MS Outlook on your PC and click on the File option.
2. Next, select the Info tab and click on Account Settings.
3. Now, from the list, select the Account Settings… option.
4. Next, select your email account and click on Change…
5. Next, click on More Settings… and open the Advanced tab.
6. Now, change the Outgoing server (SMTP) to 26 and click on OK.
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