Email Filtering: Set Up Filters to Kill Spam

What is email filtering?

Email filtering is a set of rules that automatically sort, label, forward, or delete incoming mail based on conditions you define — sender, subject, keywords, or the address it was sent to. Done well, it keeps your inbox focused and routes junk straight to trash without you lifting a finger. Done alone, it only manages spam that is already arriving. This guide covers both the how and the limit.

How email filters work

Every filter is a simple if this, then that:

• Conditions — from this sender, containing this word, sent to this address, larger than this size.
• Actions — archive, label, mark as read, forward, or delete.

The mail provider checks each incoming message against your rules and acts automatically. An email filtering service is the same idea offered as a standalone product, often with spam scoring on top — useful for custom domains, but for most people the built-in filters in Gmail or Outlook are enough.

Set up filters in Gmail

1. Open the search box, click the filter (sliders) icon.
2. Enter conditions — e.g. from: a sender, or to: a specific alias.
3. Click Create filter, choose actions (Skip Inbox, Delete, Apply label).
4. Save. It applies to new mail and, optionally, existing mail.

Tip: if you use Gmail aliases (the +tag trick), filter by the alias each service was given — one clean rule per vendor.

Set up filters in Outlook

1. Settings → Rules → Add new rule.
2. Name it, pick a condition (From / Subject includes / Sent to).
3. Pick an action (Move to folder, Delete, Mark as junk).
4. Save. Outlook also has a Junk Email list for blocking specific senders.

The limit of filtering

Filtering manages spam after it reaches you. It never stops the address itself from being spammed — you are just triaging an inbound flood. The moment a spammer rotates senders or domains, your carefully tuned rules go stale.

The durable fix pairs filtering with stopping spam at the source: give untrusted signups a disposable address so the junk never starts. See how to stop spam & junk email for the full strategy, and the do-not-mail & opt-out guide for lists you are already on.

How MoeMail fits

Filters clean up; MoeMail prevents. Use a MoeMail disposable inbox for any signup you do not fully trust — no phone number, no personal details — so it never reaches your real inbox to be filtered in the first place. No behavioural tracking, addresses auto-expire, open source (MIT), self-hostable on Cloudflare. Get a free MoeMail address.

FAQ

Do I need an email filtering service?

For most people, no — Gmail's and Outlook's built-in filters cover it. A standalone filtering service mainly helps if you run a custom domain and want extra spam scoring.

Why does spam still get through my filters?

Because filters match patterns, and spammers rotate senders, domains, and wording to dodge them. Filtering triages; it cannot stop the address from being targeted. Pair it with a disposable address to cut the source.

Can I filter by which address mail was sent to?

Yes. If you use aliases or disposable addresses, filter on the recipient — a reliable way to route or trash mail per service.