Lotus to Exchange migrations were all likely in the pre-Sarbanes Oxley and other retention regular era of email retention requirements

iirc at the time the only industries that required retention were health, legal and government

With SOX (PCI, FDIC, et al) retention laws we had another explosion of work rolling out all the compliance features of Exchange

Those were crazy times getting everybody either migrated with email or onto corporate email - there's a similar explosion of work right now with migration to M365