8782c9a87f
See https://www.mozilla.org/en-US/thunderbird/52.3.0/releasenotes/, https://www.mozilla.org/en-US/thunderbird/52.4.0/releasenotes/ and https://www.mozilla.org/en-US/thunderbird/52.5.0/releasenotes/ Fixes https://www.mozilla.org/en-US/security/advisories/mfsa2017-20/, https://www.mozilla.org/en-US/security/advisories/mfsa2017-23/ & https://www.mozilla.org/en-US/security/advisories/mfsa2017-26/ (pending)