I actually use mharc, http://www.mhonarc.org/mharc/, on my private server to archive various public lists and work-related email since it provides searching capabilities.

For work-related email, I have nmh folders I file message to for the various projects I work on and then have a cron job that runs each night that uses mharc's mh-month-pack script to copy the mail into mharc's archive area.

This system provides me an MUA-neutral way to read and search email. Since mharc keeps an mbox formatted version of all data, I can import the messages to any MUA I want, however since I still have the nmh folder data, I've never had the need.

The other advantage of my setup is I can following mailing lists w/o cluttering my inbox. I have a separate mail account I used to subscribe to lists of interest, and I archive the messages on my private server for reading and searching whenever I want.

Plus, you can define your own auto-proxy configuration file that blocks ad URLs. Therefore, when Yahoo changed there mail interface awhile back to be more "ad friendly", it did not really affect me. Though, I did get larger blank areas where big-assed ads should be.

BTW, for mozilla, the auto-proxy can redirect to a non-exist host:port to quietly drop ads in case you are unable to run a server to absorb ad proxy redirects. This works for my mother's PC where I did not want to mess with running a web/proxy server on.