Considering the Thunderbird email clients for Android and for desktop Windows, macOS, Linux are free to use and are not subscription based. Are you referring to one of the Mozilla products that is subscription based? * [https://support.mozilla.org/en-US/questions/new/mozilla-vpn/form Mozilla VPN] * [https://support.mozilla.org/questions/new/monitor/form Monitor] * [https://support.mozilla.org/questions/new/relay/form Firefox Relay] * [https://support.mozilla.org/questions/new/mdn-plus/form MDN Plus]