Labels, folders and categories
In Gmail, a label works like a folder, except that one email can carry several labels (Google). A person can create up to 5,000 labels, nest one label under another, and give each label a color (Gmail Help). An invoice from a client, for example, can carry both the client's label and an Invoices label.
Outlook splits that job between two tools. A folder is a place in the mailbox. Outlook has separate actions to move an email into a folder and to copy it there (Microsoft Support). A category is a colored tag. One email can carry more than one category and belong to several sets of related items at once (Microsoft Support).
Labels and categories are both private to the person who uses them. The people someone emails do not get their Gmail labels (Gmail Help), and other people do not see the categories someone assigns in Outlook (Microsoft Support).
Two ways labels can arrive
As folders, one copy per label
Microsoft's own Google Workspace migration converts Gmail labels to Exchange Online folders (Microsoft Learn). An email with several labels is copied into a folder for each one (Microsoft Learn). The invoice above arrives twice: once in the client's folder and once in Invoices.
Each copy takes up space. Microsoft notes that the mailbox size Gmail reports can differ from the size after label-to-folder conversion (Microsoft Learn). For its older IMAP migration, Microsoft warns that copies made from labels can make the Microsoft 365 mailbox double, or more, in size (Microsoft Learn). A person whose mail mostly carries two labels can end up with two copies of most of it.
Excluding a label leaves out its messages, not just the label. For a Google Workspace migration, Microsoft's ExcludeFolders setting takes Gmail label names (Microsoft Learn), and Microsoft describes choosing labels this way as excluding those messages from the migration (Microsoft Learn).
As categories, one copy with several tags
The other way to map labels is to give each one an Outlook category of the same name. The invoice then arrives once, carrying both categories, and the mailbox holds one copy of it. Folders still record where each email lived, such as the Inbox or Sent Items.
The two results look different on a person's first morning in Outlook. A test mailbox moved and opened before the full move shows whether people see folders or categories.
Finding mail by label in Outlook
In Gmail, a search such as label:invoices finds the emails under a label (Gmail Help). When labels arrive as folders, people open the folder instead. When labels arrive as categories, Outlook offers several ways to reach them.
- In new Outlook, a search for
category:invoicesfinds items whose category name includes that word (Microsoft Support). Outlook on the web searches the Category field the same way (Microsoft Support). - In new Outlook and Outlook on the web, a category can be added to Favorites, where it shows in the folder list (Microsoft Support).
- In classic Outlook, the Categorized search option shows only results that carry a chosen category (Microsoft Support). A Search Folder for categorized mail gathers matching messages in one place without moving or duplicating them (Microsoft Support). Microsoft lists Search Folders as only partly available in new Outlook (Microsoft Support).
Archived mail
Archiving in Gmail moves an email out of the inbox, and it stays under All Mail, so it can be found later. If someone replies to it, it returns to the inbox (Google).
Outlook also has an Archive folder. Archived items stay easy to find from the search box or the folder itself (Microsoft Support). The Archive folder is not the same as the Online Archive, which new Outlook and Outlook on the web call the In-Place Archive. Archiving an email puts it in the Archive folder, not the Online Archive (Microsoft Support).
For anyone who archives most of their mail, where that mail lands is the first thing to check in a test mailbox.
Stars, importance and inbox tabs
Stars and flags
A star marks an email as important, and Gmail offers stars of different colors and other icons (Gmail Help). Google's own comparison of Gmail and Outlook places Outlook's flags, which track important messages, beside Gmail's stars (Google). Once the flagged email list is turned on in Microsoft To Do, flagged Outlook emails also appear there as tasks. The list starts with the 100 most recently flagged emails from the last 30 days (Microsoft Support).
Microsoft documents its migration as moving mail, rules, calendars and contacts, and its pages do not mention stars (Microsoft Learn).
Important
Gmail marks emails as important on its own, from signals such as whom a person emails and how often (Gmail Help). A person can also click the marker to change it, which teaches Gmail which emails they consider important (Gmail Help).
Inbox tabs
Gmail can split the inbox into five tabs, which Google calls categories: Primary, Social, Promotions, Updates and Forums. People cannot create their own (Gmail Help). Outlook's Focused Inbox splits the inbox into two tabs: Focused and Other. The most important email appears on Focused. A person can send every future email from a sender to Other (Microsoft Support).
Gmail and Outlook use the word category differently. In Gmail, it is an inbox tab. In Outlook, it is a colored tag a person assigns.
Snooze
A snoozed Gmail email leaves the inbox and comes back at the chosen time (Gmail Help). New Outlook has Snooze, and classic Outlook does not (Microsoft Support).
Filters that applied labels
A Gmail filter can send incoming email to a label (Gmail Help). Microsoft's migration brings filters across as Outlook rules, turned off by default (Microsoft Learn). An Outlook rule can move email from chosen senders to a folder. Once created, the rule runs on incoming messages (Microsoft Support). A filter that labeled every invoice stops sorting new invoices until its Outlook rule is checked and turned on.
What to tell your people
A short note before the first day in Outlook answers most questions about labels. It can cover:
- Where labels went, as folders or as categories, and how to search for a category by name.
- Where archived mail went, and that the Archive folder is not the Online Archive.
- What a flag does, and where flagged email shows up.
- That Outlook sorts the inbox into Focused and Other, which work differently from Gmail's five tabs, and that category now means a tag.
- Which rules came across turned off, and who checks them.
- What works on phones. Microsoft's pages disagree on whether the Outlook phone app can assign categories. A comparison table says no on iOS and Android (Microsoft Support), and an iOS page says email can be categorized there (Microsoft Support). Checking the current app first avoids a wrong promise.
How MigrationSanity moves labels
MigrationSanity runs the move for you, and every Gmail label becomes an Outlook category of the same name. A message with three labels arrives once and stays findable under all three. The place it lived in Gmail, such as the Inbox or Sent, becomes its Outlook folder.
What people find in Outlook
- Nested labels keep their full path in the category name, such as Clients/Acme.
- Label colors are not copied. Each category takes a color from Outlook's palette.
- Mail archived from the Gmail inbox lands in the Outlook Archive folder, with its labels as categories.
- Starred mail arrives flagged. Someone who uses star types other than the yellow star also gets a category in the matching color for each type, such as Red star or Green check.
- Gmail's Important marker and snoozes are not carried.
- Spam and Trash are not migrated, and the report shows how many messages each held.
- A later run does not reapply labels changed in Gmail after a message moved. The report counts the messages this affects.
Where MigrationSanity goes further than Microsoft's own tools
- Who runs the move
- Microsoft's own tools, by defaultYour Microsoft 365 administrator (Microsoft Learn)
- MigrationSanityRun for you. A few of your people move first, and you check them before the full move
- A message with several labels
- Microsoft's own tools, by defaultCopied into a folder for each label (Microsoft Learn)
- MigrationSanityArrives once, with a category for each label
- Stars
- Microsoft's own tools, by defaultMicrosoft does not mention stars. Its documented scope is mail, rules, calendars and contacts (Microsoft Learn)
- MigrationSanityStarred mail arrives flagged. Someone who uses star types other than the yellow star also gets a category in the matching color for each type
- Contact labels
- Microsoft's own tools, by defaultGmail tags and custom tags are not migrated (Microsoft Learn)
- MigrationSanityLabels you created become Outlook categories, and starred contacts get a category too
The Microsoft column describes the documented default of Microsoft's Google Workspace migration. The MigrationSanity column describes the service shown on the How it works page and the migration behavior in the Known Limitations documents each client receives. Known Google limitations summarizes those documents.
Vendor pages checked October 2026. Microsoft and Google change their tools often, and the linked pages are the reference.