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Troubleshooting email client warnings about invalid server certificates

After you install AVG Internet Security or AVG AntiVirus Free, some third-party email clients, such as Microsoft Outlook, Mozilla Thunderbird, SeaMonkey, or The Bat!, may show that the mail server certificate is invalid when you send and receive emails.

AVG Email Shield uses an advanced scanning method for incoming and outgoing emails over SSL/TLS secured connections. Microsoft Outlook, Mozilla Thunderbird, Sea Monkey, and the Bat! have their own certificate stores and may require extra configuration to avoid warnings about invalid server certificates.

This article explains how to stop warnings about invalid mail server certificates by exporting the Email Shield certificate, then importing it into your email client's certificate store.

Export Email Shield certificate

  1. Open AVG AntiVirus and go to MenuSettings.
  2. Click the Search icon in the top-right corner.
  3. Type geek:area into the text box, and select AVG Geek from the search results.
  4. Scroll to the Email Shield section. Ensure the box next to Scan SSL connections is ticked, then click Perform next to Export certificate.
  5. Select a location to save the exported Email Shield certificate (for example, your Windows Desktop) and click Save.
  6. Click OK in the AVG Information dialog.
  7. Import the Email Shield certificate into your email client.
Each email account in your mail client needs to be configured as required by your mail provider. Refer to your mail client's and mail provider's documentation for instructions.

Import Email Shield certificate

  1. In Mozilla Thunderbird, click Menu (three lines) ▸ Options.
  2. Select Privacy & Security in the left panel.
  3. Scroll to the Certificates section, then click Manage Certificates...
  4. Select the Authorities tab, then click Import...
  5. Locate the Email Shield certificate you previously exported from AVG AntiVirus, select the file, then click Open.
  6. Tick Trust this CA to identify websites, then click OK.
  7. When the Certificate Manager screen appears again, click the Servers tab.
  8. Ensure that there is no entry for AVG Email Scanner. If this entry exists, delete all certificates connected to AVG Email Scanner in the Servers tab. Then, click OK to save the changes.

The AVG Email Shield certificate is now imported to Mozilla Thunderbird.

  1. In SeaMonkey, click EditPreferences....
  2. Click the arrow next to Privacy & Security to expand the section.
  3. Select Certificates, then click Manage Certificates....
  4. Select the Authorities tab, then click Import....
  5. Locate the Email Shield certificate you previously exported from AVG AntiVirus, select the file, then click Open.
  6. Tick Trust this CA to identify websites and click OK.
  7. When the Certificate Manager screen appears again, click the Servers tab.
  8. Ensure that there is no entry for AVG Email Scanner. If this entry exists, delete all certificates connected to AVG Email Scanner in the Servers tab. Then, click OK.
  9. Click OK in the Preferences window to apply the changes.

The AVG Email Shield certificate is now imported to SeaMonkey.

  1. In The Bat!, click ToolsAddress Book.
  2. Click View, then select Certificate Address Books.
  3. Right-click Trusted Root CA, and select New Contact from the context menu.
  4. Type AVG Email Shield in the First name field.
  5. Select the Certificates tab.
  6. Click Import....
  7. Locate the Email Shield certificate you previously exported from AVG AntiVirus, select the file, then click Open.
  8. When the Email Shield certificate appears in the Certificates tab, click OK to apply the changes.
If you are using Microsoft Outlook via the website https://outlook.live.com/, you do not need to import the Email Shield certificate.
  1. In Microsoft Outlook, click the File tab.
  2. Select Options in the bottom-left corner of the screen.
  3. Click Trust Center.
  4. Select Trust Center Settings.
  5. Click Email Security.
  6. Click Settings....
  7. Next to Signing Certificate, select Choose....
  8. Click More choices, then select the certificate you want to use.
  9. Click OK to save your changes.

The AVG Email Shield certificate is now imported to Microsoft Outlook.

  • AVG Internet Security 21.x for Windows
  • AVG AntiVirus Free 21.x for Windows
  • Microsoft Windows 10 Home / Pro / Enterprise / Education - 32 / 64-bit
  • Microsoft Windows 8.1 / Pro / Enterprise - 32 / 64-bit
  • Microsoft Windows 8 / Pro / Enterprise - 32 / 64-bit
  • Microsoft Windows 7 Home Basic / Home Premium / Professional / Enterprise / Ultimate - Service Pack 1 with Convenient Rollup Update, 32 / 64-bit

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