Can't empty deleted items folder - Outlook 2016 / Exchange Online Plan 1

Hi Chris

Thanks for your reply and the suggested article which has certainly given me some useful notes for next time I have a problem

In the end as the mailbox is critical to our business (process incoming mail for a document management system), I logged a support call with Microsoft and a really helpful chap advised it was due to the 14 day retention policy on mailbox not working and used some powershell commands to get it working

So fingers crossed the 60000+ items in deleted items has now started to go down and 99% of my 50Gb used is now 85% so much improved

Thank you for your reply