Sitecore.EXM.Extension.config

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:role="http://www.sitecore.net/xmlconfig/role/">
  <sitecore role:require="Standalone or ContentManagement">
    <pipelines>
      <DispatchNewsletter role:require="!DedicatedDispatch">
        <processor type="Sitecore.EmailCampaign.Cm.Pipelines.DispatchNewsletter.SendMessage, Sitecore.EmailCampaign.Cm" resolve="true">
          <patch:delete/>
        </processor>
        <!-- The WaitForDispatchToFinish pipeline processor should only be enabled if you have at least one dedicated dispatch server enabled. If you enable this processor you should disable the SendMessage processor. -->
        <processor type="MyNamespace.WaitForDispatchToFinishExt, MyAssembly" resolve="true" patch:before="*[@type='Sitecore.EmailCampaign.Cm.Pipelines.DispatchNewsletter.MoveToSent, Sitecore.EmailCampaign.Cm']">
          <TimeToWaitBetweenChecks>1000</TimeToWaitBetweenChecks>
        </processor>
      </DispatchNewsletter>
    </pipelines>
  </sitecore>
</configuration>