Getting your Microsoft 365 environment off to a good start: tenant name, branding and SharePoint sharing

Microsoft 365 · Appelez le tech

The first hours of a Microsoft 365 environment (a “tenant”) settle things that are almost impossible to change later. The name chosen at sign-up, the sign-in page your employees will see and the SharePoint sharing rules deserve ten minutes of thought before you click “Next.”

1. The name before .onmicrosoft.com: the most permanent choice

When you create the tenant, Microsoft asks you for a name. It becomes your starting domain and, above all, the address of your SharePoint and OneDrive sites:

This initial name can’t be changed. Microsoft does offer a SharePoint domain rename, but it’s a heavy operation: every site is renamed one by one, some Power Automate flows and Teams tabs must be recreated, deleted sites can no longer be restored, and it’s limited to twice in the life of the tenant. Better to choose well from the start.

• Think ahead: a generic name ages better than one tied to a partner or a product.
• Never use the real name for a trial tenant: it would be taken and hard to get back.
• In a merger or acquisition, plan for the name question before migrating.

Your custom domain, from the start

• Add it in the Microsoft 365 admin center (Settings > Domains) and create the requested DNS records.
• Set up SPF, DKIM and DMARC so your email reaches its destination and nobody can impersonate you.
• Create accounts with the company domain address from the start, to avoid an address migration later.

2. Sign-in page branding

Your logo and a background image on the Microsoft sign-in page give a professional environment and help employees recognize their page. It isn’t protection against phishing on its own (hackers copy logos too), but a blank page or one that looks different from usual becomes a warning sign.

Where: Microsoft Entra admin center (entra.microsoft.com) > Entra ID > Custom Branding (Company branding). Licence: Microsoft 365 Business Standard, Entra ID P1 or P2, or SharePoint Plan 1.

• Sign-in page text (1,024 characters): for example “Access restricted to employees. Need help? 1 833 444-1041.” It’s public: no sensitive information.
• Language: add a French version (“Add browser language”).
• Your image only appears once the email address is entered, and personal Microsoft accounts don’t see it.
• CSS customization is being retired in 2026: stick to images and text.

3. SharePoint and OneDrive sharing rules

By default, Microsoft 365 is set up to make sharing easy. For an SMB that handles confidential data (client files, personal information covered by Quebec’s Law 25), a few settings need tightening before employees start sharing.

Where: SharePoint admin center > Policies > Sharing.

Settings to adjust on day one

• Default link type: “Specific people.” Employees choose who they share with, rather than sending a link that works for anyone.
• If “Anyone” links remain allowed: require an expiry (for example 7 to 30 days) and limit them to view-only.
• Guest access expiration: external access is removed automatically after the number of days you choose (for example 90).
• OneDrive at the same level or more restrictive than SharePoint: that’s where employees most often share without thinking.
• Allowed or blocked domains: limit sharing to your partners’ domains if your situation allows it.
• Sensitive sites more locked down than the global level: each site can be set more restrictively.
• Entra ID invitation settings: decide who is allowed to invite external users. They apply on top of the SharePoint settings.

The starter checklist