Hi, looking at moving exchange on prem to online to get the benefits especially with MFA. Currently unsure about the plan needed as users are on a Microsoft 365 Business Basic plan which has exchange and MFA built in. I think there is a further requirement to to purchase Azure AD Premium P1 so would just like some clarity as this will lift the monthly subscription.
If there are 100 mailboxes on exchange on prem and say 70 are user based and 30 are service mailboxes such as info@ - are a 100 licences needed if Azure AD Premium P1 is used?
Also looking for a good step by step process for carrying out the migration process and how to backup mailboxes if an email needed after the 30 day retention period.