You must ensure the reason why the users has been blocked by the Microsoft. Once done checking, you may follow below steps.
1. Reset email password for affected user.
2. To go directly to the Restricted Users page, use https://protection.office.com/restrictedusers.
3. Login using Exchange Admin (vlanexchangeadmin) of the tenant.
4. Click on the affected username or user email address, then click Unblock.
*Notes: Please acknowledge user that the email can be use after 1 hour you unblock the email.