Multi domain email migration to Office365

[Boska]

Let me apologize right off the bat, I have very little experience with Office 365, so this is probably a total newb question.  I have been asked to help a small law firm migrate to Office 365 Business.  I've done a bit of research, but I didn't easily find anything exactly like what I'm being asked to accomplish.  There are 3 lawyers and 1 receptionist.  Each lawyer has a different email domain - @domain1.com, @domain2.com, @domain3.com - They want to keep their respective domains, but they also want to be able to see each others calendar, share OneDrive, and possibly use Teams.  Is that possible with Office 365 without the need to consolidate to a single domain and use aliases?   

[#2 · Accepted solution]

@Boska 

Hi, this is absolutely possible with O365 yes.  You just need to add the 3 domains into one Office 365 tenant and verify them, and they will be able to collaborate easily.

What email platform are they currently using?

[#3]

@PeterRising 

At this time almost everyone is using some iteration of Outlook, with one exception of someone who is still, primarily, using gmail. 

It looks like tenancy is exactly what I was looking for.  I had faith there was a fairly simple way to achieve the expected results.  Thank you for the information, I appreciate the guidance!

[#4]

@Boska 

Happy to help.  Let me know if you need any further assistance! 

[#5]

Your organization can migrate email to Microsoft 365 or Office 365 from other systems. Your administrators can Migrate mailboxes from Exchange Server or Migrate email from another IMAP-enabled email system. And your users can import their own email, contacts, and other mailbox information to a Microsoft 365 or Office 365 mailbox created for them. Your organization also can work with a partner to migrate email.

Before you start an email migration, review limits and best practices for Exchange Online to make sure you get the performance and behavior you expect after migration.

See Decide on a migration path or Exchange migration advisors for help with choosing the best option for your organization.