The exim-sa package is deprecated since the previous release. It was the original implementation of SpamAssassin integration with Exim, and was functionally similar to sendmail milters or postfix filters. However, that functionality is rather limited, and Exim now has far better support for content checking, fully integrated into its general-purpose Access Control Lists.

Since the sa_exim feature was not enabled in the default configuration, the package can normally be safely uninstalled to allow Exim to be upgraded. Users who have modified their configuration to use sa_exim features should either reconfigure to use Exim's full content scanning abilities or rebuild the package for themselves to include the exim-sa subpackage. For further details on Exim's built-in content scanning, refer to the Exim documentation:

http://www.exim.org/exim-html-4.62/doc/html/spec_html/ch40.html