In case this helps others.
E.g. header field Date: Wed, 6 Oct 2010 15:20 +0100 (BST) is misread as 2010-10-06 16:20:00. Thunderbird and Gmail do not have this problem on the same message.
This might be confined to 4-digit date format.
I have reported this as a bug.
eM Client V10.1.4588 on Windows 7.