The update to V78 was sorted over a year ago for Enigmail. When you update to V78 the Enigmail product installs or offers a modified addon that steps you through the migration to Thunderbird's native end to end encryption. See https://support.mozilla.org/en-US/kb/introduction-to-e2e-encryption and https://support.mozilla.org/en-US/kb/openpgp-thunderbird-howto-and-faq You might want to do some background reading on the E2EE mailing list for answers to your further encryption questions https://thunderbird.topicbox.com/groups/e2ee I would suggest search there before posting. Most topics have been done to death in the past 12 months already.

Thanks Matt for the response. Is there an easy way to make a backup of the current TB installation for a restore if update does not work as expected? Martin