When using EXM 3.5 with Azure Search provider, an attempt to dispatch a newsletter to more than 1000 recipients results in only 1000 sent email messages due to Azure Search pagination limits.
To resolve this issue, install the following hotfixes: https://dl.sitecore.net/hotfix/SC Hotfix 186131-1 List Manager 1.2.5.zip https://dl.sitecore.net/hotfix/SC Hotfix 185914-1 ContactSegmentationIndex 10.0.4.zip https://dl.sitecore.net/hotfix/SC Hotfix 185911-1 Email Experience Manager 3.5.zip Note: Read the installation instructions inside each archive.