Looking to purge records and thought I may start here; we have over 600k records in this list. Trying to find a definition of what this list captures and the impact of purging these records. Trying to understand if there are any dependencies with other Marketo programs or internal systems such as SFDC.
It may depend on your system.
There are several methods to purging bad emails. And several threads here on it.
so you may not want to remove Customers or certain groups for recordkeeping, so be careful.