Home » Alerts » How to Fix Invalid Mail Server Certificates While Sending and Receiving e-mails After Avast Installation

Some third-party mail clients like Mozilla Thunderbird, SeaMonkey, or The Bat! may start showing a warning message about the inval mail server certificate while you send and receive e-mails after installing Avast 2016.

Avast 2016 has the Mail Shield feature which works transparently for most mail clients and uses an advanced scanning way for incoming and outgoing e-mails over SSL/TLS secured connections. So generally it doesn’t required any extra configuration to work with your mail provider. However, those mail clients which have their own certificate stores such as Mozilla Thunderbird, SeaMonkey, or The Bat! require additional configuration. Otherwise, they will release warnings about invalid mail server certificates whenever you will try to send and receive e-mails.

If you want to ignore such warnings about invalid mail server certificates, you need to export the Mail Shield certificate and import it to your mail client’s certificate store.

To export the Avast Mail Shield certificate:

1. Open the Avast user interface.

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2. Choose Settings

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3. In the Settings window, choose Avast active protection and then click on the option Customize next to the Mail Shield.

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4. In the Mail Shield Settings window, select SSL scanning and then click the Export certificate button…

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then confirm a location to save the exported Mail Shield certificate (for example your Windows Desktop) and then click on the Save option.

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5. A message will appear after you successfully export Avast Mail Shield, which says “Avast Mail Shield has been successfully exported”, next you need to click OK.

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6. Go to the SSL scanning section and verify that Scan SSL connection is enabled (checked) before closing the Mail Shield Settings window.

Now to exit and apply changes, click OK.

7. Now import the Mail Shield certificate into your mail client.

Specific instructions are written for three mail clients, please select your mail client :

  • Mozilla Thunderbird
  • SeaMonkey
  • The Bat!

Important Note: Every e-mail account that your mail client holds needs to be configured as required by your mail provider. So for the proper detailed instructions, refer to your mail client’s and mail provider’s documentation.

Follow the following instruction to import the Mail Shield certificate to Mozilla Thunderbird

For importing the Avast Mail Shield certificate to the Mozilla Thunderbird certificate store:

  • Click the menu icon (three horizontal lines) at the top right corner in Mozilla Thunderbird to open the Application menu and select Options….

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  • On the top right select option Advanced, then click the Certificates tab, and then click View Certificates to open the Certificate Manager.

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  • Select the Authorities tab in Certificate Manager, click Import…,

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and place the Mail Shield certificate that you exported from Avast 2016. Select the file name and then click on the option Open.

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  • Confirm the trust purpose of avast! Mail Scanner Root by click the checkbox in front of the option “Trust this CA to identify websites” and then click OK.

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  • Select the Servers tab, when the Certificate Manager screen appears again,

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…and make sure that there is no entry entitled “Avast Mail Scanner“. If any such entry exist there, delete all certificates connected to Avast Mail Scanner on the Servers tab. Once you remove all the certificates connected to the Avast Mail Scanner, click OK to close the Certificate Manager,

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…and to apply changes, click OK in the Options window.

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For importing the Mail Shield certificate to SeaMonkey

Follow the instructions below to import the Mail Shield certificate to the SeaMonkey certificate store:

  • Click the Edit menu on the top In SeaMonkey and choose Preferences….

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  • Expand the Privacy & Security group on the left in Preferences, then select the Certificates section, and click on the option Manage Certificates….

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…and save the Mail Shield certificate which you have exported from Avast 2016. Select the file name and then click on the Open button.

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  • Verify that you want to Trust this CA to identify websites and then click on the OK button.

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  • Select the Servers tab, when the Certificate Manager appears again,

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…and make sure that there is no entry entitled “Avast Mail Scanner”. If any such entry exist there, delete all certificates connected to Avast Mail Scanner on the Servers tab. Once you remove all the certificates connected to the Avast Mail Scanner, click OK to close the Certificate Manager,

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…and now to apply changes, click on the option OK in the Preferences window.

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To import the Mail Shield certificate to The Bat!

For importing the Mail Shield certificate to The Bat! Certificate store:

  • Click the Tools menu on the top In The Bat! and select Address Book.

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  • Click View on the top in Address Book and then select Certificate Address Books.

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  • On the left side of the Address Book, right-click on the option Trusted Root CA group and then select New Contact from the context menu.

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  • In the Edit Address Entry – avast Mail Scanner Root window, enter “Avast Mail Scanner Root” in the First name field under General tab.

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  • In the same window, select the Certificates tab, click Import…,

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…and save the Mail Shield certificate that you exported from Avast 2016. Select the file and click on the option Open.

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  • To apply changes, Click OK once the Mail Shield certificate is imported and exit from the Address Book.

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