As you might expect, there are a very large number of linux-related Mailing Lists that enable developers and users to communicate and collaborate on projects. These Lists cover every conceivable aspect of Linux, from the technical arcana of kernel development to the relatively unfocused discussion of issues at the newbie level. Subscribers to a particular Mailing List are generally very knowledgeable in the List's topic, and detailed and useful information is often retrievable. The communications are publically accessible through Internet search engines and in the form of online Mailing List Archives. You will typically see archived pages when you conduct a search using an Internet search engine.
Not all Mailing Lists are associated with an online archive, but this is increasingly the case. Similarly, not all archives have an associated search engine.
Initially, try locate the Mailing List Archive you are interested in by typing a keyword/s and "mailing list archive" in an Internet search engine.
For a listing of linux-related Mailing Lists, peruse websites such as the Linux Resource Exchange and the Linux Online Mailing Lists
A relatively new, excellent Mailing List resource is Geocrawler (The Knowledge Archive). This is a continuously updated, searchable archive of a large number of Lists that also allows one to register and subsequently post to any particular Mailing List. Its user interface is simple and its search function delivers messages very quickly. I highly recommend this site.
You may also find Mailing List archives at the following locations :
The website of the distribution of Linux you use.
The website/s of the Window Manager and/or Desktop Environment you use.
The website dedicated to the application or project in question.
This is not a complete listing of archives and you may find additional sites with an Internet search engine. But, this should certainly get you going.