Problem

In Jira Incoming Mail Handlers integrated with Microsoft Graph Api , when the folder name is set with subfolders such as Inbox.testfolder or Inbox/testfolder, Jira throws "javax.mail.MessagingException: Folder with name cannot be found; exception"

 MS Graph API MS Graph API[10600]: Messaging Exception in service 'com.atlassian.jira.service.services.mail.MailFetcherService$MessageProviderImpl' when getting mail: Folder with name Inbox.testfolder cannot be found
javax.mail.MessagingException: Folder with name Inbox.testfolder cannot be found;
      nested exception is:
    	java.lang.IllegalArgumentException: Folder with name Inbox.testfolder cannot be found

However, if only the Inbox has been set in the FolderName, then the Jira incoming mail handler can read emails and process them.

Workaround

Move the subfolder out of the inbox and put it on the root level of the mailbox.