Like a lot of open source developers in the KDE and GNOME communities, I use Thunderbird as my primary email client (I generally sit on the fence between KDE and GNOME anyway so not using KMail or Evolution is in fitting with that!). I have a few other clients for accessing my mail (e.g. Roundcube and on various phones and tablets via IMAP too). But when I use Thunderbird, I also use the awesome Gmane service. This free service allows you to access many of the mailing lists of the Open Source community via an NNTP interface (which Thunderbird supports well). Rather than clogging up your mail server with subscriptions to lots of messages of numerous projects (even if something like GMail would do a good job of organising this), using NNTP gives you control over when to "pull" the messages in. In most cases you can even post to the mailing list via Gmane too without having to subscribe to the list (you just have to go through a one time verification process).
Sadly one things that has always bugged me: the fact I cannot rename the newsgroups to suit my taste. I already use the Extra Folder Columns addon that lets me see additional columns in the folder listings so I had a little go at tweaking it to allow me to assign nicer names for the numerous newsgroups (well mailing lists) I follow. It turned out not to be too hard (tho' it took me a while due to not knowing anything about modding Mozilla apps!).
My patch can be found here. I'll be submitting it upstream to the guys who developed the addon and they'll hopefully incorporate it (even if it does not fit in perfectly with the name of the addon, it wouldn't really be possible to do this separately without tweaking the existing addon in some capacity).