Office 365 inter-tenant collaboration

This article describes several ways to collaborate between two Office 365 tenants. It is intended for Office 365 Administrators.

Suppose that two organizations, Fabrikam and Contoso, each have an Office 365 for business tenant and they want to work together on several projects; some of which run for a limited time and some of which are ongoing. How can Fabrikam and Contoso enable their people and teams to collaborate more effectively across their different Office 365 tenants in a secure manner? Office 365, in conjunction with Azure Active Directory B2B collaboration, provides several options. This article describes several key scenarios that Fabrikam and Contoso can consider.

Office 365 inter-tenant collaboration options include using a central location for files and conversations, sharing calendars, using IM, audio/video calls for communication, and securing access to resources and applications. Use the following tables to select solutions and learn more.

Exchange Online collaboration options

Sharing goal

Administrative action

How-to information

Share calendars with another Office 365 organization

Administrators can set up different levels of calendar access in Exchange Online to allow businesses to collaborate with other businesses and to let users share the schedules (free/busy information) with others

Sharing in Exchange Online

Organization relationships in Exchange Online

Create an organization relationship in Exchange Online

Modify and organization relationship in Exchange Online

Remove an organization relationship in Exchange Online

Share calendars with external users

Control how users share their calendars with people outside your organization

Administrators apply sharing policies to users mailboxes to control who it can be shared with and the level of access granted

Sharing policies in Exchange Online

Create a sharing policy in Exchange Online

Apply a sharing policy to mailboxes in Exchange Online

Modify, disable, or remove a sharing policy in Exchange Online

Configure secure email channels and control mail flow with partner organizations

Administrators create connectors to apply security to mail exchanges with a partner organization or service provider. The connectors enforce encryption via transport layer security (TLS) as well as allowing restrictions on domain names or IP address ranges your partners send email from.

How Exchange Online uses TLS to secure email connections in Office 365

Configure mail flow using connectors in Office 365

Remote domains in Exchange Online

Set up connector for secure mail flow with a partner organization

Mail flow best practices for Exchange Online and Office 365 (overview)

SharePoint Online and OneDrive for Business collaboration options

Sharing goals

Administrative action

How-to information

Share sites and documents with external users

Administrators configure sharing at the tenant, or site collection level for Microsoft account authenticated, work or school account authenticated or guest accounts

Manage external sharing for your SharePoint Online environment

Restricted Domains Sharing in Office 365 SharePoint Online and OneDrive for Business

SharePoint Business to Business Collaboration: Extranet for Partners with Office 365

Tracking and controlling external sharing for end users

OneDrive for Business file owners and SharePoint Online end users configure site and document sharing and establish notifications to track sharing

Configure notifications for external sharing for OneDrive for Business

Share sites or documents with people outside your organization

Skype for Business collaboration options

Sharing goal

Administrative action

How-to information

Skype for Business Online - IM, calls, and presence with other Skype for Business users

Administrators can enable their Skype for Business Online users to IM, make audio/video calls, and see presence with users in another Office 365 tenant.

Allow users to contact external Skype for Business users

Skype for Business Online - IM, calls, and presence with Skype (consumer) users

Administrators can enable their Skype for Business Online users to IM, make calls, and see presence with Skype (consumer) users.

Let users add external contacts from Skype

Azure AD B2B Collaboration options

Sharing goal

Administrative action

How-to information

Azure AD B2B collaboration - Content sharing by adding external users to a group in an organization's directory

A global admin for one Office 365 tenant can invite people in another Office 365 tenant to join their directory, add those external users to a group, and grant access to content, such as SharePoint sites and libraries for the group.

What is Azure AD B2B collaboration preview?

Azure AD B2B: New updates make cross-business collab easy

Office 365 external sharing and Azure Active Directory B2B collaboration

Azure Active Directory B2B collaboration API and customization

Azure AD and Identity Show: Azure AD B2B Collaboration (Business to Business

Office 365 collaboration options

Sharing goal

Administrative action

How-to information

Office 365 Groups - Email, calendar, OneNote, and shared files in a central place

Groups are supported in Business Essentials, and Business Premium, and the Enterprise E1, E3, and E5 plans. People in one Office 365 tenant can create a group and invite people in another Office 365 tenant as guest users. Applies to Dynamics CRM as well.

Learn about Office 365 groups

Guest access in Office 365 Groups

Deploy Office 365 Groups

Yammer collaboration options

Sharing goal

Administrative action

How-to information

Yammer - Collaboration through an enterprise social medium

Unless the ability to create external groups is disabled by a Yammer admin, users can create external groups to collaborate in Yammer through conversations, the ability to like and follow posts, share files, and chat online.

Create and manage external groups in Yammer

Points to be aware of about Office 365 inter-tenant collaboration

Each organization maintains its own user accounts, identities, security groups, subscriptions, licenses, and storage. People use the collaboration features in Office 365 together with sharing policies and security settings to provide access to needed information while maintaining control of company assets.

  • User accounts:    Accounts cannot be shared and accounts cannot be duplicated between the tenants or partitions in the on-premises Active Directory Directory Services.

  • Licenses & subscriptions:    In Office 365, licenses from licensing plans (also called SKUs or Office 365 plans) give users access to the Office 365 services that are defined for those plans.

  • Storage:    In Office 365 plans, software boundaries and limits for SharePoint Online are managed separately from mailbox storage limits. Mailbox storage limits are set up and managed by using Exchange Online. In both scenarios storage can't be shared cross tenants.

No. Vanity domains, such as fabrikam.com or tailspintoys.com, can only be associated and used with one tenant at the time. Each tenant must have its own namespace; UPN, SMTP and SIP namespaces cannot be shared across tenants.

On-premises hybrid components, such as an Exchange organization and Azure AD Connect, cannot be split across multiple tenants.

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