Warning :Export files were not generated during Campaign Launch, because no export list format is as

Hi All,

  We are facing the above warning, due to which we are seeing that no emails are been sent to user even though the campaign is launched with no error.

When we launch the campaign using lists, we are able to successfully execute the campaign in system tasks we see that there is warning and then we dont see any default merge happening.. and no emails sent.

This started after we updated the NQHOST in symbolic strings to integrate OBIEE to Siebel, we have reverted back to vanila but still we are seeing the above warning. No emails are going.