How to Create Email Filters and Rules to Sort Business Mail

Filters are the difference between an inbox that fills with receipts and notifications and one that only shows mail a person needs to read. This guide shows where to create rules so they run even when your computer is off, which filters pay off first for a small business, and the mistakes that quietly hide customer mail.

Quick summary

• Receipts and invoices: From contains "invoice", "receipt" or your card provider, move to Finance. Keep them unread so the bookkeeper sees the count.
• Notifications from tools: From ends in a SaaS domain (github.com, stripe.com, your project tool), move to Notifications and mark read. Check that folder twice a day, not each time it pings.
• Customers: To or Cc contains support@ or sales@, add a flag or label "Customer" and leave in Inbox. This is the mail that must never be hidden.
• Newsletters: header List-Unsubscribe exists, move to Reading. Most webmail filters can match on headers; if yours cannot, match on the word "unsubscribe" in the body.
• Your own domain: From ends in @yourcompany.com, label "Internal". Useful when you later search for anything a colleague sent.

Server-side or in the app?

A rule created in webmail runs on the mail server the moment a message arrives, so your phone, laptop and a colleague sharing the mailbox all see the sorted result. A rule created in Outlook desktop or Apple Mail runs only when that program is open, and other devices see the unsorted inbox until it catches up. Create rules on the server whenever your host offers it (many use the Sieve standard behind the scenes) and use app rules only for cosmetic things like colours.

The five filters every small business should have

1. Receipts and invoices: From contains "invoice", "receipt" or your card provider, move to Finance. Keep them unread so the bookkeeper sees the count.
2. Notifications from tools: From ends in a SaaS domain (github.com, stripe.com, your project tool), move to Notifications and mark read. Check that folder twice a day, not each time it pings.
3. Customers: To or Cc contains support@ or sales@, add a flag or label "Customer" and leave in Inbox. This is the mail that must never be hidden.
4. Newsletters: header List-Unsubscribe exists, move to Reading. Most webmail filters can match on headers; if yours cannot, match on the word "unsubscribe" in the body.
5. Your own domain: From ends in @yourcompany.com, label "Internal". Useful when you later search for anything a colleague sent.

Creating a rule in common apps

• Webmail (most hosts): Settings, Filters or Rules, then Add. Choose the condition (From, To, Subject, header), the action (move, flag, mark read, forward) and save. Rules apply to new mail only unless there is a "run on existing" option.
• Outlook desktop: right-click a message, Rules, Create Rule. The full editor is at File, Manage Rules and Alerts. Rules with "client-only" in the description do not run on the server.
• Apple Mail: Mail, Settings, Rules. These run only on that Mac.
• Thunderbird: Tools, Message Filters. Runs on that computer, but you can tick "run periodically" to catch mail that arrived while it was closed.

Write conditions that do not misfire

• Prefer exact domains over words. "From contains bank" catches a customer whose surname is Bankole; "From ends with @yourbank.com" does not.
• Match on the To or Cc line for role addresses, because filters on "Subject contains support" miss most customer mail.
• Order rules carefully. If "Notifications" runs before "Customers" and a customer replies through your ticket tool, the customer rule never sees it. Put customer rules first and use "stop processing" after them.
• Never auto-delete. Move to a folder you empty monthly instead; a filter that deletes has no undo.

Shared mailboxes and filters

On a shared support@ mailbox the server-side rules are the only ones that make sense, because three people's Outlook rules would fight each other. Put the rules on the mailbox itself in webmail, and keep them minimal: usually one rule that files automated notifications and nothing else. On OquMail every mailbox on the free plan has webmail, so the shared support@ inbox can carry its own rules while each teammate keeps a personal set on their own address.

Common questions

Why did my rule not apply to old mail?

Most server-side filters only act on new arrivals. Look for an option like "apply to existing messages" or "run now". If it is missing, select the old mail by searching for the same condition and move it by hand once; the rule handles everything from then on.

Can filters forward mail to another person?

Yes, most rule editors offer forward or redirect. Use redirect for customer mail so the customer stays in the From line and the recipient can reply directly. Be aware that forwarding to a different provider can fail SPF checks at the destination; forwarding between mailboxes on the same host is safer.

How many rules is too many?

When you stop remembering what they do. Five to ten well-named rules cover almost every small business. If you find yourself creating a rule per sender, the real fix is unsubscribing or turning off the notification at its source.