Oh my! Did you verify the size of the main.log file? 2TB of mail.log data strikes me as too much. Are you rotating your logs? Is there a lot of spam moving through your system?
Assuming you are running this on an ext3 filesystem you cannot increase the maximum file size beyodn 2TB. If you really do need bigger files than that then you should think about XFS or ext4. Exim does not have a max supported log size... at least I could not find it in the docs and I've never had that problem when running exim.
Can you double check the size of mail.log and that is being rotated?
--------------------------------- Geoff Galitz Blankenheim NRW, Germany http://www.galitz.org/ http://www.galitz.org/ http://german-way.com/blog/ http://german-way.com/blog/