Hi,
We currently have about 160,000 Office365 mailboxes for our University and I need to try and track whether a message with a specific subject or from a specific sender was delivered to any mailboxes in the organisation. I am running a "Get-Mailbox | Search-Mailbox" cmdlet now, however it is horrendously slow and looking like it will take around 2-3 weeks to complete which is useless. Is there a faster way to check the message tracking logs? I wouldn't mind if this took even a couple of hours, however in this instance we are trying to track down a phishing message that very specifically targets our organisation and is highly likely to dupe the users that recieve it.
Cheers
Andy