From the Wikipedia “Cypherpunk” artice (2018-05-26):
The Cypherpunks mailing list was started in 1992, and by 1994 had 700 subscribers. At its peak, it was a very active forum with technical discussion ranging over mathematics, cryptography, computer science, political and philosophical discussion, personal arguments and attacks, etc., with some spam thrown in. An email from John Gilmore reports an average of 30 messages a day from December 1, 1996 to March 1, 1999, and suggests that the number was probably higher earlier. The number of subscribers is estimated to have reached 2000 in the year 1997.
While an incarnation of the mailing list is still in operation (archives viewable here) it is generally acknowledged that its heyday was in the 90s through to around 2000. The (incomplete) archive of posts from this era can be found at mailing-list-archive.cryptoanarchy.wiki. If you want to read a comprehensive description of what the list is/was all about, you can read The Cyphernomicon which is the “official” mailing list FAQ, compiled by Timothy C. May. It’s quite lengthy but if you have the time, it is worth the read.
It is during this period that the community was energised by a battle with the US intelligence establishment relating to the export of cryptography (which the US Government had at the time classified as a munition). This is a battle that the cypherpunk movement and broader civilian cryptography community largely won, though some variations of government proposals still pop up to this day.
Reading the archives, you will notice that while it was subject to the usual trolling and spam, like most online communities both then and now, it had high signal to noise ratio. High quality technical discussion relating to maths and cryptography is found on the list.
This community inspired a generation of people to start viewing this relatively arcane branch of mathematics (assymetric cryptography - itself only about 20 years old at the time) as a powerful tool for social change. Armed with these ideological convictions and technical toolsets, many cypherpunks made great contributions. Notable list participants include Julian Assange, the founder of Wikileaks, and Hal Finney (the receiver of the first Bitcoin transaction). Assuming Satoshi Nakamoto (the creator of Bitcoin) was not Finney himself, then this mysterious figure was also most likely a list subscriber (and maybe participant).
The modern cryptocurrency space can largely be considered as an offshoot of the community first formed on the Cypherpunks Mailing List.
The main eras of the list can roughly be categorised as follows:
More information about this can be found in a section of the Cypherpunk Wikipedia page.