Avast 2015: Warnings about invalid mail server certificates when sending and receiving e-mails

Summary

After installing Avast 2015 some 3rd party mail clients like Mozilla Thunderbird, SeaMonkey, or The Bat! may start to show a warning message that the mail server certificate is invalid when you send and receive e-mails.

The Mail Shield in Avast 2015 uses an advanced scanning method for incoming and outgoing e-mails over SSL/TLS secured connections, which works transparently for most mail clients. Therefore it normally does not need any extra configuration to work with your mail provider. However mail clients which have their own certificate stores like Mozilla Thunderbird, SeaMonkey, or The Bat! need additional configuration. Otherwise, you may get warnings about invalid mail server certificates when you send and receive e-mails.

To avoid such warnings about invalid mail server certificates, export the Mail Shield certificate and import it to your mail client's certificate store.

First export the Mail Shield certificate:

  1. Open the Avast user interface.
  2. Select Settings.
  3. In the Settings window select Active Protection and click Customize next to the Mail Shield.
  4. In the Mail Shield Settings window select SSL scanning and click the Export certificate button, ...then select a location to save the exported Mail Shield certificate (for example your Windows Desktop) and click Save.
  5. When a message appears that "Avast Mail Shield has been successfully exported" click OK.
  6. Before closing the Mail Shield Settings window, go to the SSL scanning section and make sure that Scan SSL connection is enabled (checked).
    Click OK to exit and apply changes.
  7. Then import the Mail Shield certificate into your mail client. Please select your mail client below to view specific instructions:
Each e-mail account in your mail client needs to be configured as required by your mail provider. Please refer to your mail client's and mail provider's documentation for instructions.

Importing the Mail Shield certificate to Mozilla Thunderbird

To import the Mail Shield certificate to the Mozilla Thunderbird certificate store:

  1. In Mozilla Thunderbird click the menu icon (three horizontal lines) at the top right corner to open the Application menu and select Options....
  2. Select Advanced on the top right, click the Certificates tab, and then click View Certificates to open the Certificate Manager.
  3. In Certificate Manager select the Authorities tab, click Import..., ...and locate the Mail Shield certificate you exported from Avast 2015. Select the file and click Open.
  4. Confirm that you want to Trust this CA to identify websites and click OK.
  5. When the Certificate Manager screen appears again, select the Servers tab, ...and ensure that there is no entry entitled "Avast Mail Scanner". If this entry exists, delete all certificates connected to Avast Mail Scanner on the Servers tab. Then click OK to close the Certificate Manager, ...and click OK in the Options window to apply changes.

Importing the Mail Shield certificate to SeaMonkey

To import the Mail Shield certificate to the SeaMonkey certificate store:

  1. In SeaMonkey click the Edit menu on the top and select Preferences....
  2. In Preferences expand the Privacy & Security group on the left, select the Certificates section, and click Manage Certificates....
  3. In the Certificate Manager select the Authorities tab, click Import..., ...and locate the Mail Shield certificate you exported from Avast 2015. Select the file and click Open.
  4. Confirm that you want to Trust this CA to identify websites and click OK.
  5. When the Certificate Manager appears again, select the Servers tab, ...and ensure that there is no entry entitled "Avast Mail Scanner". If this entry exists, delete all certificates connected to Avast Mail Scanner on the Servers tab. Then click OK to close the Certificate Manager, ...and click OK in the Preferences window to apply changes.

Importing the Mail Shield certificate to The Bat!

Mail Shield certificate to The Bat! certificate store:

  1. In The Bat! click the Tools menu on the top and select Address Book.
  2. In Address Book click View on the top and select Certificate Address Books.
  3. Right-click the Trusted Root CA group on the left side of the Address Book and select New Contact from the context menu.
  4. In the General tab enter "Avast Mail Scanner Root" in the First name field.
  5. Select the Certificates tab, click Import..., ...and locate the Mail Shield certificate you exported from Avast 2015. Select the file and click Open.
  6. Once the Mail Shield certificate is imported click OK for to apply changes and exit the Address Book.
  • Avast Premier 2015
  • Avast Internet Security 2015
  • Avast Pro Antivirus 2015
  • Avast Free Antivirus 2015
  • Microsoft Windows 10 Home / Pro / Enterprise / Education
  • Microsoft Windows 8.1 / Pro / Enterprise
  • Microsoft Windows 8 / Pro / Enterprise
  • Microsoft Windows 7 Home Basic / Home Premium / Professional / Enterprise / Ultimate
  • Microsoft Windows Vista Home Basic / Home Premium / Business / Enterprise / Ultimate
  • Microsoft Windows XP Home / Professional / Media Center Edition

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