How do you usually find documents from old email conversations?

Curious how people deal with this.

After working on projects for a while, information ends up scattered across emails, attachments and folders.

Later when I try to find something, I usually remember it like:

"the spreadsheet we reviewed before the investor meeting"

or

"the presentation we prepared for the Nordic expansion project"

not the actual file name.

Then I start searching email, browsing folders, trying different keywords.

Sometimes it works fast, sometimes it takes a while.

How do you usually find documents from older conversations or projects?