I have finally liberated myself from the mail storage format/layout of a particular mail client: I have set up a dovecot IMAP server. I’m using fetchmail to pull down mail from my SpamCop account and dovecot’s CMU Sieve plug-in for filtering. It seems to work quite well. I can point any IMAP client (including the one on my new iPhone 3G S) at endoframe.net and read e-mail in one centralized location.
The most painful part of this has been (and continues to be…I’m not done yet) moving e-mail from Evolution‘s store to IMAP folders. I am an e-mail pack rat, which means I have several very large mail folders. Unsurprisingly, these can take some time to move. More annoyingly, Evolution tends to crash at the end of moving particularly large folders. Fortunately this hasn’t resulted in any actual data loss (yet?). It seems to crash after it’s copied everything over to the new location, during deletion of the messages at the old location.