Many mailing lists are hosted on Yahoo Groups or Google Groups. When you subscribe to such a list, these companies attempt to collect lots of personal information from you and make you agree to some ridiculous and onerous terms. For example, Yahoo hides its terms in a five line text field, but if you scroll down this includes almost 5,000 words of legalese including such gems as
You agree to indemnify and hold Yahoo! and its subsidiaries, affiliates, officers, agents, employees, partners and licensors harmless from any claim or demand, including reasonable attorneys’ fees, made by any third party due to or arising out of Content you submit, post, transmit or otherwise make available through the Service, your use of the Service, your connection to the Service, your violation of the TOS, or your violation of any rights of another.
In plain English, Yahoo wants to bill you for their own attorney fees. Overall, though Yahoo’s terms are better than most. Still they’re not something a legally sane person wants to agree to. Fortunately, you don’t have to.
To subscribe to a Yahoo Groups mailing list simply send a message from the address you you wish to subscribe to email@example.com. The same trick works for Google groups, except you send the message to firstname.lastname@example.org.
Neither company advertises this feature since they really want to get you to agree to their terms and collect as much personal information from you as possible. However at least for the moment you don’t need to provide it.