In order of effect: mark junk as junk so the filter learns, block persistent senders by domain using a rule, unsubscribe from companies you recognise, and add anything important to Safe Senders so it never gets misfiled. Outlook's filter is decent out of the box; the gains come from training it and cutting off individual senders. What it cannot do is reduce how many organisations hold your address.
1. Train the junk filter
Use Report → Junk rather than deleting. Deleting teaches Outlook nothing. Reporting is a signal, and it also feeds Microsoft's wider filtering.
Check the Junk Email folder occasionally for legitimate mail that landed there — filters misfire in both directions, which is exactly why the FTC's advice includes reviewing the junk folder rather than trusting it blindly. Source: FTC. Checked: 2026-08-19.
2. Raise the filter level, carefully
Outlook offers a junk-filter strength setting. Moving it up catches more, and misfiles more. It's worth trying one step up if you're drowning — but pair it with Safe Senders (below) or you'll miss something that matters.
3. Block domains, not addresses
Blocked Senders works, but bulk operations rotate the part before the @ constantly, so blocking one address achieves very little. Block the domain instead — in Outlook you can add @example.com to Blocked Senders, which covers every address at it.
For anything more precise, use a rule: Rules → New rule, match the sender's domain, action delete or move to Junk. Rules are exact and, unlike the classifier, never change their mind. What blocking does and doesn't achieve.
4. Protect the mail you can't afford to lose
Add your bank, your employer and anything with security alerts to Safe Senders. This is the step people skip, and then a raised filter level quietly eats a fraud alert. Do it before you tighten anything else.
5. Unsubscribe — from senders you recognise only
Outlook surfaces an unsubscribe control for messages carrying a List-Unsubscribe header. Prefer it to the link in the body.
For a legitimate company this works and is legally backed. For a sender you've never dealt with, clicking anything confirms the address is live and read. How to tell them apart.
6. Sweep and archive
Outlook's Sweep handles the recurring-sender case well: delete everything from this sender, or keep only the latest. It doesn't reduce incoming volume but it clears the backlog quickly, which is often what makes the inbox feel unusable.
What about Outlook aliases?
Microsoft accounts support additional addresses that deliver to the same mailbox, and Outlook also supports plus-addressing (you+shop@outlook.com).
Plus-addressing is useful for filtering your own mail and for spotting which company leaked you — but it's not privacy: your real address is visible inside it, list-cleaning strips the tag routinely, and there's no way to switch a single tag off. The same analysis applies as for Gmail.
Every step here works on messages after they've arrived. None reduces the number of organisations holding your address, and that number only grows. A well-tuned Outlook keeps the inbox tidy while the underlying exposure keeps increasing — which is a boundary of what any receiving mail provider can do, not a criticism of Outlook.
Going beyond that ceiling means changing what you hand out rather than how it's sorted: a different address per service, so mail arriving where it shouldn't names its own source and can be cut off. How to run that, or the full picture across all four mechanisms.
Microsoft's own help pages are authoritative on any interface detail, and the menus move between versions — check there if a step doesn't match what you see. More: the Gmail equivalent.