Color Coding in Mac Mail (2026): Flags, Rules and Colors

Mail, the email app built into macOS, gives you three ways to color code email: flags (pick a color from the Flag button and rename each color to mean something), rules that tint the background or text of matching messages automatically (Mail > Settings > Rules, action Set Color of Message), and manual color through Format > Show Colors. Only flags show up on your iPhone; message colors stay on the Mac.

Color is the fastest filter there is. Before you read a single subject line, you can see which emails are from a client, which ones need an answer today and which are just receipts. The catch is that Mail spreads color across three features that behave differently, so it's easy to set something up and then wonder why your iPhone doesn't show it. This guide covers each method on macOS, when to use which, and the usual reasons colors fail to appear.

Which color coding method should you use?

Use flags when color means "do something about this", and rules when color means "this came from someone or something specific". Manual colors are for a one-off. The table sums up how each one behaves on macOS, based on Apple's guides to flags and color coding.

I lean on flags for anything I have to act on and keep rule colors for who an email is from. Mixing the two jobs in one system is where color coding stops being useful: if red means both "urgent" and "from my manager", it ends up meaning nothing.

How to color code emails with flags in Apple Mail

Flagging a message on a Mac takes two clicks: select it, click the Flag button in the toolbar and choose a flag color. The flag appears in the message header, and the email also shows up in the Flagged mailbox in the sidebar. These are the steps in Apple's Mail User Guide for macOS 27:

1. In Mail, select one or more messages in the message list.
2. Click the Flag button in the toolbar, then choose a flag.

To remove a flag, select the flagged messages, click the Flag button and choose Clear Flag.

Rename flag colors so they mean something

Mail lets you rename each flag color, so "Red" can read "Urgent" everywhere it shows up. Apple's guide uses exactly that example. The Flagged mailbox only lists the individual colors once you've used more than one flag.

1. In the Mail sidebar, click the disclosure arrow next to Flagged.
2. Click a flag's name, then click it again so the name becomes editable.
3. Type the new name and press Return.

My own set is short. Red is "Reply today", yellow is "Waiting on someone", blue is "Read later", and the other colors stay unused. Three meanings is about the limit of what I can remember at a glance; past that I'm reading the legend instead of the inbox.

Apple's guide for macOS Sequoia (macOS 15) adds that renamed flags carry over to your other Macs when iCloud Drive is turned on with Mail selected in its options.

Find and filter flagged email

To see one color at a time, expand Flagged in the sidebar (or in the Favorites bar) and choose a flag. Click Inbox to go back to everything. You can also search: type a flag's name in the search field and pick the suggestion under Flags, or type "flag" and pick the suggestion under Status, per Apple's guide. For more ways to slice the inbox, our guide to Apple Mail search and Smart Mailboxes goes deeper.

How to color emails automatically with rules

A rule in Apple Mail can color every incoming message that matches a condition, such as a sender's address or a word in the subject. You set it in Mail > Settings > Rules with the action Set Color of Message, then choose the background or the text. Apple's color coding guide gives these steps:

1. Open Mail > Settings from the menu bar and go to the Rules tab.
2. Click Add Rule and type a name in the Description field.
3. Choose whether any or all of the conditions must be met.
4. Set the condition with the pop-up menus, for example From and contains, then type the sender's address or domain.
5. In the Perform the following actions pop-up menus, choose Set Color of Message, then choose whether it colors the background or the text.
6. Choose a color from the pop-up menu, or choose Other to pick any shade in the Colors window.
7. Click OK.

Mail then asks whether to apply the rule to the messages already in your mailboxes. Apple's rules guide explains that if you skip it, the rule only touches new mail; you can run it on existing messages later with Message > Apply Rules, or Control-Command-L from Apple's keyboard shortcuts list.

I learned that one the slow way. The first color rule I made seemed to do nothing, because I'd told Mail not to apply it and was staring at an inbox of old messages. Pressing Control-Command-L colored them in a second.

Color rules worth setting up

Rules work best on things that don't change: who sent the email and what kind of email it is. A few that hold up well, all built from the From and Subject conditions:

• One client, one color. From contains the client's domain, background in a pale color. Every thread from anyone at that company stands out.
• Your manager's email in colored text. From contains their address, text color set to something strong. Text color is less loud than a background and still easy to spot.
• Billing in gray. Subject contains "invoice" or "receipt", set to match any. Low-priority mail fades back instead of competing.
• An account in its own shade. If you read several accounts in one inbox, one rule per account, each with a condition that matches that account's address, gives each account its own tint.

When a new client project starts, I add a domain rule before anything else. It takes a minute, and from then on their emails jump out of a busy inbox without any sorting.

Flag messages automatically with a rule

Rules can also flag mail for you, which gives you color that does sync to your iPhone. Apple's guide doesn't list every rule action, but rules have long been able to mark messages as flagged, as Macworld's walkthrough of Mail rules shows. Apple doesn't print that action's exact name, so look in the Perform the following actions menu, near Set Color of Message, for the item that marks a message as flagged, and matching messages arrive already flagged. Use this sparingly; flags you didn't set yourself pile up fast.

How to color messages by hand with Format > Show Colors

To color one or a few emails without a rule, select them in the message list, choose Format > Show Colors and click a color. Mail changes the background of the selected messages, per Apple's color coding guide.

1. Select the messages in the Mail message list.
2. Choose Format > Show Colors from the menu bar.
3. Click a color in the Colors window.

This is handy for marking a handful of messages for a single task, such as the emails you need for an expense report. Apple's guide doesn't cover removing a manual color, so think of it as a short-term marker and use flags for anything you'll want to clear later.

Can you color mailboxes or folders in the Mail sidebar?

No. None of the color options Apple documents for Mail apply to the sidebar: flags color messages, and rules and Format > Show Colors color rows in the message list. The closest substitutes are the per-color entries under Flagged, which act like colored folders, and Smart Mailboxes, which gather matching email without moving it. If you're coming from Gmail, where labels carry their own colors, the Gmail labels explainer shows how those work and why Mail's model is different.

Why your color coding isn't showing up

When colors go missing in Apple Mail, the cause is usually that you're looking on another device, the rule is off or never ran on old mail, or another rule acted first. Work down this list:

1. You're on your iPhone or iPad. Apple's color coding guide says colors set by a rule or by hand are visible only on your Mac. Flags are different: Apple's iPhone guide says flags appear on that email on all your Apple devices using the same Apple Account.
2. The rule is turned off. In Mail > Settings > Rules, a rule only runs when its checkbox is selected, per Apple's Rules settings page.
3. The rule never ran on existing mail. Select the messages and choose Message > Apply Rules (Control-Command-L).
4. Another rule got there first. Rules run in the order they're listed, and Mail stops applying rules to a message once it hits a Stop Evaluating Rules action or once a server rule has moved the message to another mailbox, per Apple's rules guide. Drag your color rule higher in the list.
5. The condition doesn't match. Check the address in the rule against the message header. A client who writes from a second domain needs a second condition, with the rule set to match any.
6. Your mail provider changes the flag color. Some Mac users on the Apple Support Community report that one of their accounts turns every flag red after it syncs, while another account keeps the colors. Apple doesn't document this, but it points at the provider's server rather than Mail. If one account keeps losing colors, flag a message in a different account and see whether the problem follows the account.

Rules sync between Macs too. Apple's rule settings page says rules are available on your other Macs with iCloud Drive turned on and Mail selected, though files attached to rules, such as sounds or scripts, don't come along. A color rule you make on a laptop can quietly start tinting mail on your desktop Mac.

Other Mail features that do a similar job

Color is one way to make important email stand out; Apple Mail has two others that need no setup at all, both in Apple's guide to marking emails to revisit:

• VIPs. Click the star next to a sender's name in the message header to make them a VIP. Their mail collects in a VIP mailbox, and Apple caps the list at 100 people.
• Follow Up suggestions. If you send an email and get no reply in 3 days, Mail can resurface it above the rest of your inbox. Switch it with the Follow Up Suggestions option in Mail's settings.

I use VIP for the handful of people whose email always comes first, which frees the flag colors for tasks. Keyboard users can speed all of this up with the shortcuts in our Apple Mail keyboard shortcuts guide.

A simple color system you can set up in ten minutes

Color coding pays off when it's small and consistent. If you're starting from nothing:

• Rename three flags for actions: reply today, waiting on someone, read later. Leave the rest alone.
• Add one rule per key client or account with a pale background color.
• Add one gray rule for invoices and receipts so they recede.
• Apply rules to existing mail once, with Control-Command-L.
• Clear flags as you finish the task, so red keeps meaning "today".
• Check your iPhone shows the flags, and don't expect the rule colors there.