If Thunderbird is specified as your system's default email application, it will integrate with other applications (such as word processors and web browsers). For example, when you click an email address link (like "This email address is being protected from spambots. You need JavaScript enabled to view it.") on a web page or invoke a mail function (such as "Send to") from a word processor, Thunderbird will launch and open a message composition window.

Force Thunderbird to check if it is the default

Thunderbird can be configured to check if it is the operating system's default mail client each time it is started.

1. At the top of the Thunderbird window, click the Tools menu and select Options, or click the menu button  and choose Options.
2. On the Advanced panel, select the General tab.
3. Make sure that "Always check to see if Thunderbird is the default mail client on startup" is checked.
4. Click Check Now to check if Thunderbird is set as the default mail client immediately.

• If you want to set Thunderbird as the default client for e-mail, newsgroups or feeds, check the corresponding boxes and click OK. When a box is grayed out, Thunderbird is already set as the default client for that purpose.
• If you set Thunderbird to be the default mail client, other applications (such as your web browser or word processing application) may need to be restarted for the changes to take effect.

Set Thunderbird as the operating system default

Set Thunderbird as an application default

In some cases (such as Firefox on KDE Linux), the application doesn't check the operating system preferences to determine the default email application. When that is the case, you must set the default in the application itself. Refer to the application documentation for instructions.

How to Create a PFX Certificate File from a PEM File

Issue

Some certificate authorities (such as RapidSSL) only supply certificate in the form of a PEM file, which is not usable by many Windows services.

In the case of RapidSSL, the PEM file may not have been generated as a part of a certificate signing request.

How to Convert PEM to PFX

• Install the latest stable Open SSL. The main page is here or you can find good Windows binaries here.
• Copy the PEM file to the OpenSSL binary folder, such as C:\Program Files\OpenSSL-Win64\bin
• Open an administrative command prompt or Powershell window to that folder
• Type in:

.\openssl pkcs12 -export -out result.pfx -inkey mypemfile.pem -in mypemfile.pem

• You will be prompted for a PFX password as part of the process. You must securely store the password with the PFX file to be able to use it.
• Above, the -inkey command is used to input the private key. If you have a separate certificate signing request (CSR) this would likely not be in the .PEM file, but would be in a separate .CRT file:

.\openssl pkcs12 -export -out result.pfx -inkey mycsrkeyfile.crt -in mypemfile.cer

Also see here.

Applies to:

• Windows Server services that require a PFX certificate that includes the private key

The PKCS#12 or PFX format is a binary format for storing the server certificate, any intermediate certificates, and the private key into a single encryptable file. PFX files are usually found with the extensions .pfx and .p12. PFX files are typically used on Windows and macOS machines to import and export certificates and private keys.

Requirements

• The original private key used for the certificate
• A PEM (.pem, .crt, .cer) or PKCS#7/P7B (.p7b, .p7c) File
• OpenSSL (included with Linux/Unix and macOS, and easily installed on Windows with Cygwin)

The commands below demonstrate examples of how to create a .pfx/.p12 file in the command line using OpenSSL:

PEM (.pem, .crt, .cer) to PFX

openssl pkcs12 -export -out certificate.pfx -inkey privateKey.key -in certificate.crt -certfile more.crt

Breaking down the command:

• openssl – the command for executing OpenSSL
• pkcs12 – the file utility for PKCS#12 files in OpenSSL
• -export -out certificate.pfx – export and save the PFX file as certificate.pfx
• -inkey privateKey.key – use the private key file privateKey.key as the private key to combine with the certificate.
• -in certificate.crt – use certificate.crt as the certificate the private key will be combined with.
• -certfile more.crt – This is optional, this is if you have any additional certificates you would like to include in the PFX file.

PKCS#7/P7B (.p7b, .p7c) to PFX

P7B files cannot be used to directly create a PFX file. P7B files must be converted to PEM. Once converted to PEM, follow the above steps to create a PFX file from a PEM file.

openssl pkcs7 -print_certs -in certificate.p7b -out certificate.crt

Breaking down the command:

• openssl – the command for executing OpenSSL
• pkcs7 – the file utility for PKCS#7 files in OpenSSL
• -print_certs -in certificate.p7b – prints out any certificates or CRLs contained in the file.
• -out certificate.crt – output the file as certificate.crt

Clear the group policy cache on a machine

way one

1. Open My Computer/Computer
2. In the URL or address bar paste: %windir%\system32\GroupPolicy
3. Right click and delete the: Machine and User folders to clear local group policy cache
4. Restart the computer to reapply the group policies

You can also run the little PowerShell oneliner as Administrator to remove the Group Policy folder and all files below:

Remove-Item "$env:windir\system32\GroupPolicy" -Force -Recurse

way two

1. Delete the “HKLM\Software\Policies\Microsoft” Key (looks like a folder).
2. Delete the “HKCU\Software\Policies\Microsoft” Key
3. Delete the “HKCU\Software\Microsoft\Windows\CurrentVersion\Group Policy Objects” Key.
4. Delete the “HKCU\Software\Microsoft\Windows\CurrentVersion\Policies” Key.

third way

1. Remove the computer from the domain – (change to a Workgroup)
2. Restart computer
3. Run gpupdate /force
4. Rejoin the domain