Most of the specific details can be set by the mailing list administrator, and often by each individual member of the list. The topic of discussion on a mailing list varies from list to list. There are mailing lists that discuss everything from gardening to television shows to computer programming. Regardless of the topic, it is nearly always advisable to keep your posts on the assigned topic of that group. Most mailing lists are small in size when compared to Usenet newsgroups .
Mailing lists are also usually more controlled than newsgroups.
Mailing lists do have their disadvantages, however. Because all messages are sent as e-mail, one must read through every message, regardless of the subject. With thousands of mailing lists to choose from, it can be quite difficult to find the one you're looking for. If you know of any web pages devoted to the topic you are looking for, check those pages to see if a mailing list is mentioned. You can also ask other people on the Internet who are interested in the desired topic if they know of any mailing lists.