How to Create Filters in Proton Mail (Simple and Sieve)

Proton Mail has two ways to create a filter: a point-and-click builder for simple conditions, and a Sieve script editor for anything more complex. Both live under Settings > All settings > Proton Mail > Filters, and both run on Proton's servers before mail reaches your inbox — not inside the app on your phone or laptop.

That server-side detail matters more than it sounds like it should. A filter you set once applies to Proton Mail on the web, the iOS and Android apps, and any desktop client connected through Bridge, because the sorting happens before the message is delivered to any of them.

Below: the exact steps for both builders, worked rules for newsletters, invoices and client mail you can copy, a comparison table of what each builder can and can't do, and the fixes for the three reasons a saved filter quietly does nothing.

Before you start#

Decide which builder you need before you open it, because switching later means rebuilding the logic. The simple builder covers the large majority of real filtering needs: route invoices to a folder, label everything from one client, star a VIP sender.

Reach for Sieve only when a rule genuinely needs logic the checkbox interface can't express — combining conditions with OR across three fields, matching a pattern instead of exact text, or setting a vacation responder with its own timezone. Proton lets you build a filter in the simple interface and then open it in the Sieve editor to see the generated code, which is the fastest way to learn the syntax.

How to create a simple filter#

1. 1

   Open the Filters settings page

   Sign in at mail.proton.me and go to Settings > All settings > Proton Mail > Filters > Custom filters.

2. 2

   Start a new filter

   Select Add filter. Give it a short, specific name — you'll be scanning this list again in six months.

3. 3

   Set the condition

   Choose the field to match — sender, subject, or message content — and the value, such as "contains invoices@" or "subject contains receipt." Add more than one condition and choose whether all of them or any one of them must match.

4. 4

   Choose the action

   Pick what happens when the condition matches: move to a folder (including Spam), apply a label, or mark the message as starred. Paid plans can also trigger an automatic reply.

5. 5

   Save and activate

   Save the filter, then confirm its toggle is switched on. A saved-but-inactive filter is the single most common reason a filter appears to do nothing.

6. 6

   Set its priority if you have more than one

   Filters run in the order they're listed. Drag a filter by its handle to move it earlier or later if two filters could both match the same message.

Three filters worth setting up first#

Most inboxes only ever need a handful of filters to stay organized. These three cover the mail that piles up fastest, and each one maps directly onto the simple builder's condition-and-action shape.

• Newsletters and marketing mail — condition: subject contains "unsubscribe" (most marketing platforms insert this footer text automatically). Action: label "Newsletters" and move to a Newsletters folder, so they're out of the inbox but still searchable later.
• Invoices and receipts — condition: subject contains "invoice" OR subject contains "receipt," set to match any. Action: move to a Finance folder. Add your accountant's domain as a second condition if you forward statements to them.
• One recurring client or vendor — condition: sender contains their domain, e.g. "@clientdomain.com." Action: label with their name and star, so their mail is both filed and visible at a glance without hunting through a folder.

How to write a Sieve filter#

For logic beyond the builder, go to the same Filters page and select Add sieve filter. This opens a plain-text editor where you write a Sieve script directly — the same underlying language your simple filters compile down to.

A minimal script that files anything from a domain into a folder and flags it looks like this:

What Sieve can do that the simple builder can't#

Proton's Sieve implementation supports extensions the checkbox interface has no controls for: variables you can reuse across conditions, regular-expression matching instead of exact text, date-based logic, and vacation responders with their own start and end times and timezone. It can also read your contact list and contact groups, so a rule can match "anyone in my Clients group" rather than a hardcoded address.

The regex extension is the one that pays off fastest for invoices and receipts, since it can match a pattern instead of a fixed string — for example, catching any subject that looks like an invoice number rather than only the exact word "invoice." A vacation rule with a real start and end date, set once in Sieve, also survives a forgotten toggle better than the basic auto-reply switch does.

The trade-off is that a broken Sieve script is a broken script — there's no dialog box catching a typo for you. Test a new script on a low-stakes folder before pointing it at your inbox.

Simple builder vs Sieve: what each one is actually for#

The two builders share the same underlying engine, so nothing you do in Sieve conflicts with a filter you built in the simple interface — they run in the same ordered list. The difference is expressiveness, not architecture.

Why is my Proton filter not working?#

Three causes account for most filters that seem to do nothing. First, the filter is saved but its toggle is off — check the list on the Filters page, not just the filter you last edited.

Second, a message that Proton's own spam detection already classified as spam does not reach your custom filters at all; spam filtering runs first, and once a message is routed to Spam, your folder and label rules never see it. If mail is disappearing into Spam that you expected a filter to catch, fix it with an allow-list entry, not a custom filter.

Third, when two filters could both apply to the same message, non-conflicting actions all run — a message can be both labeled and starred by different filters — but conflicting actions on the same field resolve to whichever filter is lower in the list. Reorder filters by dragging them, and put the more specific rule above the more general one.

A faster way to keep sorting without maintaining rules#

Filters are durable once they're right, but every new vendor, client or subscription is another rule to write and another one to eventually clean up. AI Emaily connects to Proton Mail through Bridge and adds a layer on top of your email filters: instead of matching a fixed condition you wrote once, it reads new mail against a Personal Context brain you set up — who your clients are, what you consider urgent, what's routine — and files, drafts or flags it accordingly, without you writing a new rule for every sender.

It sits alongside your existing Sieve and simple filters rather than replacing them; approve-before-send stays on by default, and nothing here trains on your mail. We build AI Emaily.