How to Create an Outlook Rule to Categorize Emails by Project or Client

You receive many emails daily and need to organize them by project or client quickly. Outlook rules can automatically sort incoming messages based on specific criteria like the sender or subject line. This article explains how to set up rules that apply color categories to your emails as they arrive.

How Outlook Rules Work with Categories

An Outlook rule is a set of conditions and actions. When an email meets the conditions you set, Outlook performs the actions automatically. For organizing by project or client, the most common condition is the sender’s email address. You can also use words in the subject line or sent to a specific email address.

The action you will use is assigning a category. Categories are color-coded labels you can create and rename, like “Project Alpha” or “Client XYZ.” When a rule applies a category, the email appears with that colored flag in your inbox, and you can sort or filter your view by it. You must create your categories in Outlook before you can assign them in a rule.

Prerequisites Before You Start

Ensure you are using a Microsoft 365 subscription or Outlook 2021, 2019, or 2016. The steps are similar across these versions. You also need an email account added to Outlook, such as a Microsoft 365 work or school account, or an Outlook.com account. IMAP and POP accounts support basic rules, but advanced server-side rules require Exchange or Microsoft 365.

Steps to Create a Rule for a Specific Sender

This method is best for categorizing all emails from a particular client or project member.

1. Create your category first
   Right-click an email in your inbox and select Categorize > All Categories. Click New, type a name like “Client ABC,” choose a color, and click OK twice.
2. Open the Rules dialog
   Go to the Home tab on the ribbon. In the Move group, click Rules, then select Manage Rules & Alerts.
3. Start a new rule from a template
   In the new window, click New Rule. Under Start from a blank rule, select Apply rule on messages I receive and click Next.
4. Set the condition
   In the condition list, check the box next to from [people or public group]. In the rule description pane at the bottom, click the underlined phrase “people or public group.” Select a contact from your address book or type an email address, then click OK. Click Next.
5. Choose the categorize action
   In the action list, check the box for assign it to the category [category name]. In the description pane, click the underlined “category name.” Select the category you created earlier and click OK. Click Next.
6. Add any exceptions and finish
   You can add exceptions, like unless the subject contains specific words. Usually, click Next to skip. Name your rule, for example “Categorize emails from Client ABC.” Check the box for Run this rule now on messages already in “Inbox.” Click Finish, then Apply and OK to save.

Creating a Rule Based on Subject Line Keywords

Use this method when project emails contain a specific code or keyword in the subject.

1. Follow steps to create a category and new rule
   Create a category named for your project. Open Rules > Manage Rules & Alerts > New Rule and select Apply rule on messages I receive.
2. Select the subject condition
   On the condition screen, check with specific words in the subject. Click the underlined “specific words” link in the description pane.
3. Add your keywords
   In the dialog box, type words like “Project Phoenix” or “INV-2024.” Click Add after each one, then OK. Proceed to the next step.
4. Assign the category and complete
   On the action screen, check assign it to the category and select your project category. Name the rule, enable the option to run on existing messages, and finish the wizard.

Common Mistakes and How to Avoid Them

Rule Does Not Run on New Emails

If emails are not being categorized, first check if the rule is enabled. Go to Rules > Manage Rules & Alerts. In the Email Rules tab, ensure the checkbox next to your rule is selected. Also, verify the condition is correct. Edit the rule and double-check the email address or keyword spelling.

Category Is Not Visible in the Inbox

You may need to add the Categories column to your inbox view. Right-click the column headers, select Field Chooser, and drag the Categories field into your header row. Also, the rule might apply the category but the reading pane does not show the color immediately. Try switching to a different folder and back to refresh the view.

Rule Runs on Unwanted Emails

This happens when the condition is too broad. A subject rule with the word “meeting” will catch all emails containing that word. Edit the rule and add an exception, or make the condition more specific by combining multiple criteria, like from a specific person and with specific words in the subject.

Client-Based Rules vs. Project-Based Rules: A Comparison

Item	Client-Based Rule	Project-Based Rule
Primary Condition	Sender’s email address	Keywords in subject or body
Best Use Case	All communication from a single company or contact	Emails from multiple senders about one initiative
Stability	High – sender address rarely changes	Medium – depends on users including the keyword
Setup Complexity	Low – just select a contact	Higher – must define and communicate keywords
Example Category Name	“Contoso Ltd”	“Q4 Website Launch”

You can now automatically sort your inbox by applying color categories with rules. Test a new rule with a single important client first to confirm it works as expected. For advanced control, explore creating rules that also move categorized emails to a specific folder. Use the shortcut Ctrl+Shift+V to quickly apply a category to any selected email manually.