In order to have a clear audit trails in situations where organizations to whom emails have been sent claim not to have received them, do what alaveteli does (https://github.com/sebbacon/alaveteli/blob/master/app/models/exim_log.rb) and store fragments of mail logs associated to campaigns, displaying them in the admin interface.
In order to have a clear audit trails in situations where organizations to whom emails have been sent claim not to have received them, do what alaveteli does (https://github.com/sebbacon/alaveteli/blob/master/app/models/exim_log.rb) and store fragments of mail logs associated to campaigns, displaying them in the admin interface.