Did they at one point offer unlimited, or was it always just a really large amount (which in today's landscape isn't that large anymore).

It was 1Gb initially, then on their 1st birthday 2Gb and slowly growing daily, which seemed practically unlimited compared to other email that were offering 100Mb at the most? A quick look at an article[1] at the time (who claimed it was "outrageous") show Hotmail were offering 250Mb and Yahoo had just launched 1Gb to catch up.

[1] https://www.searchenginejournal.com/gmail-rewards-users-with...

They never exactly offered unlimited, it was just that the limit was constantly going up. You could watch your total storage ticking.