Firefox
# Open the '''Advanced EncryptionOptions/Preferences''' window:
#* On Windows: Pull down the '''Tools''' menu and select '''Options…'''
#* On Mac: Pull down the '''Thunderbird''' menu and select '''Preferences...'''
# Select/Unselect the check-boxes indicating the trust bits, then click on '''OK''
# Click on OK in the '''Certificate Manager'''
# Close the '''Advanced EncryptionOptions/Preferences''' window
Thunderbird
# Open the '''Advanced CertificatesOptions/Preferences''' window:
#* On Windows: Pull down the '''Tools''' menu and select '''Options…'''
#* On Mac: Pull down the '''Thunderbird''' menu and select '''Preferences...'''
# Select/Unselect the check-boxes indicating the trust bits, then click on '''OK''
# Click on OK in the '''Certificate Manager'''
# Close the '''Advanced CertificatesOptions/Preferences''' window
'''Important:''' This change will be permanent, such that it can only be changed again by you. This change will not be affected by upgrading to newer versions of Mozilla software.