Subscribe and unsubscribe to the Subversion mailing lists at http://subversion.tigris.org/servlets/ProjectMailingListList.
The tigris.org archiver tends to get stuck so it's best to use the mailing list archives at http://svn.haxx.se/ - you will find Subversion dev and users lists plus the Tortoise dev list there.
There is also a mail/news gateway at http://www.gmane.org/, to use this set up an account on your nntp news client for news.gmane.org and subscribe to any of:
Note that articles expire on some of the gmane news lists so they aren't terribly useful as an historical record, see the Archives section for this.