New Outlook Classic Style: Enable It, Rollout Details and Tenant Branding Issues

Here's what the setting does, where to find it, why some people don't see it yet, and what it changes for IT admins.

What Microsoft actually announced​

The feature is in Microsoft 365 Message Center post MC1458476, dated August 21, 2026, according to Tony Redmond of Office 365 for IT Pros. BetaNews reported Microsoft's summary of it: Microsoft is introducing an optional setting in Outlook on the web and new Outlook for Windows to mimic classic Outlook's look and feel. It helps users transitioning from classic Outlook by adjusting visual style and layout.

Microsoft says the scope goes beyond a new color scheme. When enabled, the setting applies coordinated changes across the Outlook experience, including visual styling, layout, typography, icons, and selected interactions. Microsoft also says it's meant to give a more familiar experience while maintaining the capabilities of the new Outlook.

Key facts from the notice:

• Off by default for most people. It will be off by default for most users. As part of a phased rollout, Microsoft will enable the setting by default for some users moving from classic Outlook to the new Outlook. Those users can change the setting at any time.
• Classic Outlook isn't affected. This setting affects only the experience in Outlook on the web and the new Outlook for Windows. It does not affect the user interface or behavior of classic Outlook for Windows.
• It doesn't migrate anyone. This feature does not automatically migrate users from classic Outlook to the new Outlook and does not affect or override any existing administrator configurations used to manage new Outlook availability or migration experiences.
• Timeline. The setting is off by default, can be toggled anytime, and rolls out globally from August to October 2026. No admin action is required.

In short: this is a per-user change to how Outlook looks. It doesn't migrate mailboxes, and it doesn't touch classic Outlook.

How to turn it on​

The steps are simple once the feature reaches your mailbox:

1. Open New Outlook for Windows (or Outlook on the web).
2. Click the gear icon to open Settings.
3. Go to General > Appearance.
4. Check Enable classic Outlook style.

BetaNews gives the same path: open up Settings and head to General and then Appearance. You can then check the Enable classic Outlook style box.

Munish Sethi tested the setting in September and published some useful details. It's a checkbox, not a toggle, and it sits in its own "Classic Outlook" section between the mode picker and Themes. He also points out an easy mistake: the older "Classic themes" drop-down on the same page is a different feature that only offers the old color themes. If you only see that drop-down, the new setting hasn't reached your mailbox yet.

What success looks like​

When the setting is on, a banner appears at the top of the Appearance page saying some settings aren't available in classic Outlook style. Redmond notes that Microsoft hasn't said which settings are affected. In Sethi's testing, the Themes section (Copilot themes, image themes and color themes) was greyed out, while light, dark and system modes still worked. That's one person's observation, not an official list.

Don't see it yet?​

That's probably the staged rollout. Redmond reports that Microsoft expected all Targeted Release tenants to have the style by late September 2026, with general availability following and worldwide coverage expected by late October. Sethi says admins who want it sooner can put a small pilot group on Targeted Release. He found that in the Microsoft 365 admin center under Settings > Org settings > Organization profile > Release preferences. In his case the option appeared about four to five hours after the switch, though Microsoft says such changes can take up to 24 hours. Keep in mind that Targeted Release gives those users every Microsoft 365 change early, not just this one.

In short: it's one checkbox under General > Appearance. If it's missing on October 3, your tenant probably just hasn't received it yet.

What changes on screen​

Windows Latest reports these changes after turning the setting on. They're the reviewer's observations, not a complete Microsoft spec:

• Title bar: New Outlook's blue patterned title bar is replaced by a plain dark background.
• Navigation bar: Microsoft has made the background darker in dark mode, and you've got monochrome outlines for the Mail, Calendar, People, and other app icons. Parmar also mentions a new Calendar view with the classic style.
• Folder list: It's more compact, and the icons next to folders such as Inbox, Drafts and Sent Items are gone.
• Ribbon: If you're in the mail view, you can see a Send / Receive tab alongside File, Home, View, and Help. The blue "New mail" button also becomes a neutral "New Email" button and copies Outlook Classic's iconography.
• Compose window: Message, Insert, Format Text, Draw and Options tabs run across the top, with formatting controls in the ribbon below.

Sethi adds that the Mail settings get reorganized into sections classic Outlook users will recognize, such as Message List, Reading Pane, Templates, Quick Parts, Conditional formatting, Search folders and Quick steps. He also suggests a few optional tweaks to get even closer to the old look:

He also warns that menu locations change between builds. If something isn't where you expect, use the search box at the top of Settings.

Redmond, who has used classic Outlook since 1997, says the result is close enough that he sometimes forgets which client he has open. The File menu is very different between the two, and that's the quickest way to tell them apart.

In short: the title bar, icons, folders, ribbon and compose window all change. The look is close enough to confuse a 29-year classic Outlook user.

The admin catch: organizational branding​

This rollout has caused a real problem for some IT admins. On Microsoft's Q&A forum, admins reported that company logos and navigation colors set in the Microsoft 365 admin center stopped showing in Outlook. One admin wrote that SharePoint and OneDrive continue to show CamCore branding, but Outlook on the web now shows the standard blue Outlook header with no organisation logo. The timing appears to align with MC1458476. The same post says the tenant had "Prevent users from overriding their theme" turned on.

A reply in that thread posted as a Microsoft Support response tied the behavior to Microsoft's ongoing Outlook user experience rollout referenced in Message Center Notification MC1458476. Another poster said Microsoft was engaging their internal Outlook engineering/product channels to verify whether this is a known issue or regression associated with the MC1458476 rollout.

It's more than a cosmetic annoyance. One MSP in the thread said clients rely on organizational colors to tell their real tenant apart from phishing pages, and some thought they'd been hacked when the branding disappeared. As of the latest posts in the thread, there was no confirmed fix or timeline, and no tenant-level control to bring the old branding back. If help desk calls about a "different-looking Outlook" go up this month, this may be the reason.

Admins should also know what isn't available. According to Sethi, at the time of writing there's no admin control to force the classic style on or lock it in place. It's a user preference. Redmond also raises the question of whether Microsoft will ever let admins set it.

In short: expect "why does Outlook look different?" tickets, and possibly missing tenant branding. There's no admin setting to enforce the style yet.

"Just a web app"? The architecture argument​

Now for the headline. Windows Latest describes New Outlook as "still a web app running in an Edge-powered container" and calls it a RAM hog. The complaint about web-based clients is common. Microsoft's documentation describes the client differently, though.

Microsoft Learn's overview of New Outlook says it's inspired by Outlook on the web and runs inside a "Native Windows Integration Component" using WebView2. Microsoft calls it a native application based on WebView2. Outlook on the web provides the experience, and the integration component gives it access to local machine resources such as rich notifications and fuller file access. Microsoft's WebView2 documentation describes the technology as a hybrid approach: Edge's rendering engine displaying HTML, CSS and JavaScript inside a native app.

So both sides are partly right. The interface is web-based, which is why Microsoft could restyle it so thoroughly. The web-based interface is also how Microsoft can push a restyle like this to everyone without a traditional build update. But calling it "a website" leaves out the native integration layer Microsoft documents. Windows Latest didn't publish any memory measurements, device specs or comparisons, so treat "RAM-hogging" as the reviewer's opinion rather than a test result.

Is the theme a substitute for a native app? That's an opinion too. Microsoft presents it as a way to ease the move to New Outlook. Nothing in the evidence shows Microsoft considered and rejected a different architecture.

In short: "web app" describes how the interface is built, but it's not the whole picture, and the RAM claim wasn't measured.

Looks familiar, works differently​

The most important thing for users is that the new style changes how Outlook looks, not what it can do. Microsoft says no functionality is lost, and Redmond calls it a skin. It also adds nothing. New Outlook still doesn't support COM add-ins, according to Microsoft Learn, which recommends web add-ins instead. Any classic Outlook feature that's missing in New Outlook is still missing with the classic style turned on. A familiar ribbon may make people expect the old behavior, so admins should be clear about this when they talk to users.

Will it work? Redmond thinks Microsoft made a smart move, and he says it'll be interesting to see whether users treat the style as a real bridge or just a cosmetic change. Classic Outlook users mostly know the interface from muscle memory, and this setting brings much of that layout back. It probably won't satisfy people whose objections are about add-ins, offline behavior or performance. It may well satisfy people who mainly disliked the new look and button placement.

If you're managing the switch to New Outlook, the to-do list is short:

• Brief the help desk that some users moving from classic Outlook may get the style turned on automatically.
• Pilot it with a Targeted Release group if you want to see it before general availability.
• Check your tenant branding in Outlook on the web and New Outlook, and add your case to support if your logo or colors are missing.
• Tell users that it looks like classic Outlook but works like New Outlook, including for add-ins.

Microsoft has made New Outlook look a lot like classic Outlook. Whether that's enough to win over the holdouts is a separate question.