I was part of the small team that added Exchange Offline mode very, very late in the product cycle specifically to counter the Notes Local Replication story.

We were asked for something quick and easy, but decided to put the effort in to make it the correct way for the Exchange architecture.

The bulk of that code is still there 30 years later.

Kudos, as an owner of an offline/sync stack myself - this stuff is so hard at scale. You guys did a great job!