Access Denied: This error is caused by a well-known bug in the IMAP implementation used by your email server. This typically affects IMAP servers known as MDaemon email servers.
When asked to produce a list of folders, IMAP servers must indicate whether each folder can be accessed. Because of the bug, the IMAP server indicates that certain folders can be accessed when they are in fact inaccessible. Typically (i.e., for MDaemon email servers), these folders are anti-spam/Public Folders such as "Public Folders/Bayesian Learning". When MigrationWiz later finds that the folder cannot be accessed, the migration is considered failed because of potential data loss, and stops with an "Access Denied" error.
Grant Permission to All Folders
Check to see if your IMAP server has a configuration option allowing mailbox owners to access content in all folders, including Public Folders, stored within the mailbox.
Filter Inaccessible Folders
If your IMAP server does not offer any such configuration option, consider excluding folders which are inaccessible. For Mdaemon IMAP servers, filtering all folders under Public Folder should work. Learn more about filtering folders.