Summary In MailStore, if you are archiving from Microsoft 365 mailboxes, the following error occurs: “EWS Error Code: ErrorItemNotFound” This issue was reported in (but… Read more
https://www.mailstore.com/en/help/knowledgebase/mailstore-ews-error-code-erroritemnotfound-when-archive-email-from-a-microsoft-exchange-server-or-microsoft-365/