Exchange Mailbox Agent (M365) - Spool Copy

Hi ​@Erase4ndReuseMedia 

Good day!

Yes, technically a Storage Policy with Spool Copy enabled on the Primary Copy can be associated.
However, it is not recommended for Exchange Mailbox Agent backups.

Spool copy is not a persistent backup copy, It acts like a temporary staging area, Data is immediately aged/pruned once Aux Copy runs Data exists only until it is copied to another synchronous copy

For Exchange Mailbox Agent: Restore operations depend heavily on Primary copy

Commvault explicitly supports recovery from secondary copies when primary is unusable

Recommended Design (Best Practice)

For Exchange Mailbox Agent:

• Primary Copy → Standard (non-spool) copy with retention
• Secondary Copy → Long-term or DR copy

Reference

Recovering Data From Secondary Copy for Exchange Mailbox