You may be expecting the timestamps of your logfile to use UTC but it is showing a different timezone. Can you tell if the timestamp is using the same time as the server?
You read a log file on your server that contains timestamps, and the timestamp is way off. It is more than likely your server is using a different timezone, and the logfile is matching it.
You can verify if the logfile timestamp is matching the server's time by comparing the output of these two commands.
Current server time:
Sun Aug 30 10:47:22 CDT 2020
Show the end of the logfile as it is written. (use Crtl-C to break)
# tail -fn0 /var/log/exim_mainlog
2020-08-30 10:47:17 SMTP connection from [127.0.0.1]:56348 (TCP/IP connection count = 1)
2020-08-30 10:47:17 SMTP connection from (localhost) [127.0.0.1]:56348 closed by QUIT
In this instance, you can see the timestamp and server time match, meaning the time display is in CDT.