Microsoft Exchange Licensing
If users share the same mailbox, they are required to have a USL for each user for that mailbox.
Exchange Online is licensed by user. Since a mailbox is not a user, no additional licenses are required.
In Volume Licensing, you do not need an Exchange External Connector license for outside contractors or business partners.
There’s no External Connector License with Exchange, it’s included with the Server license. Secondly, they are not hosting Exchange on behalf of another organization which eliminates SPLA.
Does Exchange USL has the equivalency of on premise CAL with SA?
If a customer purchased Exchange Online through the CSP program, what must they do to add additional seats in the middle of their agreement?
The CSP can choose to bill annually or monthly, but the licensing allows you to add or delete seats on any given month.
Can I downgrade a user from Exchange Online Plan 2 to Exchange Plan 1 in CSP?
The CSP partner sets the price and can determine if you bill monthly or annually. The program is designed similar to SPLA with its flexibility.