On 64 bit Arch Linux, my system's timezone is set to US/Central /etc/localtime -> /usr/share/zoneinfo/US/Central I work for a company in the US/Eastern time zone so the "work" user account on my computer has the US/Eastern timezone exported as an environment variable in several places (.bashrc, .profile, .xinitrc, .xprofile) export TZ=":/usr/share/zoneinfo/US/Eastern" In Thunderbird 52 (and earlier) this worked as expected. Starting with Thunderbird 60, the "Date" and "Received" columns are reflecting the system's timezone instead of the user's timezone. The issue persists with a fresh profile. This is probably related/duplicate of the following question even though the poster's system timezone and TZ variable seem to be in agreement: https://support.mozilla.org/en-US/questions/1229111 Edited to include colon when TZ is pointed to a zoneinfo file per https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html (does not fix the issue, a fixed solution is below, but it is the correct way to do things)