Microsoft 365 Business Guide: Publisher Retirement, Office 2021 End of Support and Safe Email Migration

This guide covers what the name means, what changes from plan to plan, how offline use works, and the order to follow when you move a custom-domain mailbox to Microsoft 365. The order matters more than the name: if you change one DNS record too early, new mail starts going to mailboxes that don't exist yet.

"Formerly Office 365" is mostly true​

In its March 30, 2020 announcement, Microsoft said the new names would take effect on April 21, 2020. It called the change a rename only, with no price or feature changes at that point. The main renames were:

The "Business Premium" swap confused a lot of people. The old Office 365 Business Premium became Business Standard. The name Business Premium moved to what had been Microsoft 365 Business, the bundle with security and device management.

Not every plan was renamed. Microsoft's FAQ for that announcement listed Office 365 E1, E3 and E5, F1, the A1/A3/A5 education plans and the G1/G3/G5 government plans as staying the same. That is why "Office 365" still shows up on enterprise invoices. Saying Office 365 became Microsoft 365 is broadly right for consumers and small businesses, but it is wrong as a blanket statement.

In short: for small businesses the 2020 change was a rename, with no reinstall and no new purchase. Some enterprise, frontline, education and government SKUs still use the Office 365 name.

Subscription vs. one-time purchase​

Microsoft's support comparison of Microsoft 365 and Office 2024 explains the difference:

• Microsoft 365 subscription: you get the latest app versions, including new features, security updates and bug fixes, for as long as you keep paying.
• Office 2024 one-time purchase: you pay once for apps on one PC or Mac. You get security updates but no new features, and major version upgrades aren't included. When the next release comes out, you pay full price again.
• Microsoft 365 for the web: free in a browser with a Microsoft account. It does less than the desktop apps, and it gives you no email on your own domain.

Offline use: the monthly check-in​

Installed Microsoft 365 apps keep working offline after they are installed and activated. Microsoft says you still need internet access to install and activate them, to install updates, to manage billing and to open OneDrive files unless the OneDrive sync app is installed.

The main thing to know: if the apps don't connect at least once a month, they go into reduced functionality mode and may show an unlicensed product error. To fix it, go back online and sign in to Microsoft 365. That matters for a field laptop that spends weeks off the network. If a machine really can't connect, Microsoft points to Office LTSC instead.

What's in the box depends on the plan​

Word, Excel, PowerPoint, Outlook, OneNote, Teams, OneDrive, SharePoint and Exchange Online are all familiar names, but no single bundle includes all of them on every plan. Microsoft Learn's current overview of Microsoft 365 for business breaks it down like this:

Business Premium adds the extras that matter most to IT: protection against phishing and ransomware, encryption to limit accidental sharing, and management for iOS, Android, Windows and macOS devices. One licence for the desktop-app plans covers five PCs or Macs, five tablets and five phones per user. Microsoft's small and midsized business plans are capped at 300 users.

Resellers often add a standalone Exchange Online mailbox (email and calendar, no Office apps) to the menu. If all you need is mail on your own domain, that is the cheapest way to get a Microsoft-hosted mailbox.

Choosing a plan:

• Work in a browser or on a phone? Business Basic.
• Need desktop Excel with every ribbon button? Business Standard.
• Already have email somewhere else and only want the apps? Apps for business.
• Need device management and stronger threat protection? Business Premium.

One caution: mailbox sizes and plan details vary by market and plan variant, and Microsoft changes them over time. Check the current plan page for your region before you budget around a number.

Publisher is gone​

Microsoft's message-centre reminder said that after October 1, 2026, Publisher will no longer be included with Microsoft 365 subscriptions, and Microsoft 365 subscribers will no longer be able to open or edit Publisher (.pub) files using Publisher. Microsoft's support page gives a little leeway: subscribers lose access "on or shortly after" October 1 as the removal update rolls out. So a few machines may still have Publisher this week. Don't plan around that.

Today's date matters too. As TheStreet reported, Microsoft said "Support for the perpetual version of Publisher will end on October 13, 2026, when Office LTSC 2021 and Consumer Office 2021 reach end of support". Perpetual-licence users are in a different position. Microsoft's support FAQ says if you have the Perpetual version of Publisher, although support will end, you will still be able to install and use the app beyond this date. Microsoft Q&A respondents point out that using an unsupported version may lead to security vulnerabilities and compatibility challenges over time. TheStreet also notes that the latest version of that product, Office 2024, does not include Publisher.

Some Microsoft documentation hasn't caught up. The Microsoft Learn business overview, last updated May 2026, still lists "Access and Publisher for PC only" under Apps for business and Business Standard. Microsoft's subscription comparison page still says PC users get Access and Publisher. If a sales page or a colleague tells you Publisher is included, go by the retirement notice, not the plan description.

If you still have .pub files​

1. Find them. Microsoft suggests searching for ".pub" on your PC, in OneDrive and in SharePoint.
2. Keep the layout: on any machine that still has a working Publisher licence (perpetual installs count), open the file, go to File > Save As, choose PDF and save.
3. To edit later: open the PDF in Word through File > Open. Microsoft warns that the layout may change, especially in documents with lots of graphics.
4. Converting many files: Microsoft provides a sample PowerShell script (Convert-PubFileToPDF.ps1) that converts files in bulk and supports a -Recurse switch. It needs a licensed Publisher install, and Microsoft says to test it first.
5. Rebuild templates: use Word for labels, envelopes, letterheads and newsletters, and Word or PowerPoint for flyers, brochures, business cards and certificates.

Moving your domain's email: get the order right​

The rest of this guide is where real outages happen. The MX record tells other mail servers where to deliver your mail. Change it before the new mailboxes exist and you get bounces. Change it before migrating old mail and users arrive to empty inboxes.

Setup order​

1. Buy the plan and sign in to the Microsoft 365 admin center. To add or change domains you need the Domain Name Administrator role.
2. Add and verify your domain under Settings > Domains > + Add domain. If your registrar supports Domain Connect, Microsoft 365 can confirm ownership and add the DNS records for you. Otherwise you add a TXT record by hand. Microsoft says verification can take up to 10 minutes, and some registrars take up to 48 hours. If you verify with an MX record instead of TXT, give it a high priority value so it doesn't break mail with your current provider.
3. Create users and assign licences before you touch the live MX record. Microsoft's domain guide says this keeps mail flowing without interruption when you switch providers.
4. Lower the MX record's TTL to 3,600 seconds or less before you start migrating. Other mail servers then check for the new location more often, which cuts delivery delays at cutover.
5. Migrate the old mail. IMAP migration copies only messages in mail folders. Microsoft Learn says contacts, calendar items and tasks can't be moved over IMAP and have to be moved separately, for example by importing them in Outlook. IMAP migration also doesn't create mailboxes, so every target mailbox has to exist first. A migration CSV can list up to 50,000 mailboxes and be up to 10 MB.
6. Write down your current MX record so you can roll back. Then point it at Microsoft 365 and add the other mail records it asks for.
7. Wait before shutting off the old system. Microsoft says other mail systems can take up to 72 hours to see the new MX record. Let the migration batch run for at least that long before you delete it, because mail that reaches the old system after the batch is deleted won't be copied.
8. Keep the old account until you've checked that everything you need has arrived.

Common problems​

• New mail bounces: a user had no licensed mailbox when the MX record changed.
• Inboxes are full but calendars are empty: IMAP doesn't move calendars or contacts. That is expected, not a bug.
• Mail still trickles into the old system: DNS caches haven't caught up yet. This is why you lower the TTL and wait 72 hours.
• Apps nag about licensing: the device hasn't been online for more than a month.

Reseller terms are not Microsoft policy​

A lot of small businesses buy Microsoft 365 through a hosting company or domain registrar, and the reseller's terms can affect you as much as Microsoft's. One.com's guide is a good example. It says its plans are self-managed through Microsoft's admin centre, include no automatic backup or restore, and may lose data after a grace period if the subscription is cancelled or suspended. It also says One.com's own Basic Mail addresses stop receiving mail once Microsoft 365 handles the domain.

Those are One.com's terms. Other resellers' contracts, and buying directly from Microsoft, can differ. Before you sign, ask any provider:

• Who handles recovery if a user deletes a mailbox?
• What happens to my data if a payment fails?
• Do the mailboxes I already have with you keep working when the MX record moves?

Bottom line​

Microsoft 365 isn't one fixed product. It is a group of plans that mix web apps, desktop apps, hosted Exchange mail, OneDrive storage and, at the top end, device and security management. The Office 365 name still exists in enterprise. Publisher is no longer part of the subscription, and from today the perpetual Office 2021 versions are out of support. If you're moving your business email, follow the order: verify the domain, create the users, migrate mail, move contacts and calendars separately, then change the MX record and wait 72 hours before shutting anything off.