Outlook Storage Cleanup Tool - Free Up Space

It’s usually old promotional emails, newsletters, and messages with large attachments — but Outlook doesn’t show storage per sender, so you can’t easily tell. EmailSlim scans your mailbox metadata and ranks senders and domains by total storage used, so you can see exactly what is filling your space.

Find your biggest senders and delete their emails first, rather than cleaning up message by message. With EmailSlim you scan your mailbox, see senders ranked by total storage, and bulk delete the biggest space-wasters in one click — then empty Deleted Items to reclaim the space immediately.

Yes. EmailSlim works with Outlook.com, Hotmail, and Microsoft 365 accounts. You sign in securely with your Microsoft account via OAuth, and the same storage ranking and one-click cleanup applies to all of them.

No. EmailSlim analyzes metadata only — sender, date, and size — and never reads the content of your messages. Nothing is deleted without your approval: all deletions happen in Outlook when you click delete, and they go to Deleted Items first so they stay recoverable.

Yes. You can start with a free scan of your first 500 emails, with no credit card required. EmailSlim works in any browser, so there is nothing to download or install.