1. In Thunderbird select the "Burger Menu" (three stripes) on the right and choose settings

2. Open the "Composition" tab

3. Scroll to "Addressing"

4. Check "Directory Server" and click "Edit Directories..."

5. Click on "Add" and make the following settings:

• Name, hostname and Basis-DN depending on the LDAP server. Please find the required information in LDAP for user certificates from the RA-Portal
• Port-Nummer: 636
• Bind-DN: keep empty
• Check "Use secure connection (SSL)"

Click "OK" to complete the process.

After that, the address book can be found under "Address Book" in the menu bar