KevinTheJedi Hi Kevin,
You're right, the ownership is different. Some attachments, the owner is the local "Administrators" group. Some, the owner is a local user account that was created exclusively for use by the Task Scheduler for the cron.php job to pull e-mails in. And some attachments are owned by IUSR, which I believe is some kind of default account in IIS (?).
We don't delete tickets that have attachments very often, so it's difficult to narrow down for sure if certain ownerships are causing the issue. But of the 6 or so I can check, the "administrators" group did not own any attachments that failed to delete. Only the Task User and IUSR.
I'm not sure how the cron.php task would influence the owner of attachments, or what would determine whether IUSR or anything else becomes the owner. Any ideas?
(This is a Windows server, btw).