For Cutover Migration to Office 365 Process, the first step is to Verify your domain.
The Verification Process of domain is given here:
Amid the relocation, the Simple Mail Transfer Protocol (SMTP) address of each on-premises letter box is utilized to make the email address for another Office 365 post box.
How to Verify Your Domain for Cutover Migration to Office 365 Process?
To run a cutover relocation, the on-premises area must be a confirmed space in your Office 365 association.
Sign in to Office 365 with your work or school account.
Go to the Domains page.
On the Domains- page, click Add domain to start the domain wizard.
Choose Add domain
On the Add a domain page, type in the domain name you use for your on-premises Exchange organization, and then choose Next.
On the Verify domain page, select either Sign in to GoDaddy or Add a TXT record instead for any other registrars > Next.
Follow the instructions provided for your DNS hosting provider. The TXT record usually is chosen to verify ownership.
You can also find the instructions in Create DNS records for Office 365 when you manage your DNS records.
After you add your TXT or MX record, wait about 15 minutes before proceeding to the next step.
In the Office 365 domain wizard, choose done, verify now, and you’ll see a verification page. Choose Finish.
If the verification fails at first, wait awhile, and try again.
Do not continue to the next step in the domain wizard. You now have verified that you own the on-premises Exchange organization domain and are ready to continue with an email migration.
For more details, visit : www.office.com/setup