For e.g.
Sent/Received Date of email: 2:46 pm

Time shown in reading pane: 1:46 pm

The issue has been so far seen only in the environments where the Time zone is set to UTC +3 (Istanbul) and Enterprise Vault search accessed via Internet Explorer. Turkey ended the DST observance on October 30, 2016, and the emails sent/received post this seems to be affected.
This issue has been fixed in EV 12.4.1.
The Date-time will be shown as per the current year’s time zone and DST, however if there is a change in the time zone in the past for that region, customers may observe some time difference in the search results & reading pane for older emails.
Reference: https://downloads.enterprisevault.com/
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JIRA: CFT-1830