After I deleted a folder from outside kontact (i.e. a different kontact on another computer), akonadi-ews was no longer able to synchronize the account.
The server responds with the following message (shortened and reformatted):
<?xml version="1.0" encoding="utf-8"?>
<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
<s:Header>
<h:ServerVersionInfo xmlns:h="http://schemas.microsoft.com/exchange/services/2006/types" xmlns="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" MajorVersion="15" MinorVersion="1" MajorBuildNumber="1034" MinorBuildNumber="26" Version="V2017_01_07"/>
</s:Header>
<s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<m:GetFolderResponse xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types">
<m:ResponseMessages>
<m:GetFolderResponseMessage ResponseClass="Success">
<m:ResponseCode>NoError</m:ResponseCode>
<m:Folders>
<t:Folder>
<t:FolderId Id="AAMkAGU0NjRhMTNiLTcxNWItNDQ2YS05OGQ1LWY0N2QyOTE3ZGE0OAAuAAAAAABVndXjmYa2TJeya3R3NcK5AQDbPMzgbs3fSoYAI/xeTJ7HAAAAabzMAAA=" ChangeKey="AQAAABYAAADVV7DQctuIRYeYB4MK+03/AAHv5W0h"/>
</t:Folder>
</m:Folders>
</m:GetFolderResponseMessage>
<m:GetFolderResponseMessage ResponseClass="Error">
<m:MessageText>The specified object was not found in the store., The process failed to get the correct properties.</m:MessageText>
<m:ResponseCode>ErrorItemNotFound</m:ResponseCode>
<m:DescriptiveLinkKey>0</m:DescriptiveLinkKey>
<m:Folders/>
</m:GetFolderResponseMessage>
<m:GetFolderResponseMessage ResponseClass="Success">
<m:ResponseCode>NoError</m:ResponseCode>
<m:Folders>
<t:Folder>
<t:FolderId Id="AAMkAGU0NjRhMTNiLTcxNWItNDQ2YS05OGQ1LWY0N2QyOTE3ZGE0OAAuAAAAAABVndXjmYa2TJeya3R3NcK5AQDbPMzgbs3fSoYAI/xeTJ7HAAAAafAvAAA=" ChangeKey="AQAAABYAAADVV7DQctuIRYeYB4MK+03/AACZqJhD"/>
</t:Folder>
</m:Folders>
</m:GetFolderResponseMessage>
</m:ResponseMessages>
</m:GetFolderResponse>
</s:Body>
</s:Envelope>
After I deleted a folder from outside kontact (i.e. a different kontact on another computer), akonadi-ews was no longer able to synchronize the account.
The server responds with the following message (shortened and reformatted):