Measure the volume of old emails to free up space
You are now about to migrate to Office 365. However, you would need to determine the volume taken up by the Outlook items stored in user mailboxes before starting, the ideal being to get a breakdown of Outlook messages by creation date. Then you will be able to ask users to delete or archive the oldest ones.
There is no need to consider using the tools integrated into Outlook, which are completely unusable in this case (Mailbox Cleanup tool , Search folder). Such a solution is obviously not sustainable if you have more than a couple of mailboxes to clean.
The Search-Mailbox and New-MailboxSearch cmdlets allows you to search items that meet certain criteria in all or specific mailboxes.
More interesting, it is possible to create a search in Office 365 with the Content Search eDiscovery tool in the compliance center in Office 365. However, this requires specific permissions. At the end of the day, you will still have to export the results and reprocess the information obtained to synthesize it.
Using a script
The best you can do without using a third-party solution is to run an elaborate PowerShell script using the Microsoft EWS API, for example this one for Office 365.
However, you will need to modify this script to adapt it to your own needs and maintain it in the future.
Using Promodag Reports
It is possible to automatically detect mailboxes whose users should archive old Outlook items. You can indeed achieve such a search using Promodag Reports and the Item Breakdown by Age report.
All user mailboxes can be selected, whether they are hosted in on-premise Exchange or in Office 365. You can also select mailboxes by attribute. For example, all users from the Sales Department or from a given Exchange database. This can come handy if you have actually planned to migrate them next week.
Specific folders or sets of Outlook folders can be also be selected, for example the Inbox root, or all default Outlook folders.
You can set an elaborate filter to only select certain Outlook items, for example the unread ones or those that have attachments.
You can select up to six time intervals.
Finally, you get the overview you need directly. Simply group your mailboxes by display name to get the details by user.
The most ergonomic and fastest way to measure the volume occupied by old messages in mailboxes is to use Promodag Reports. You can test this report for free and explore the many options of Promodag Reports during a 45-day evaluation period. Take advantage of it and join our community of users! You can also contact us if you would like to submit your suggestions, comments or support requests.