So far, I've been using IMAP to read my mail. However, I have about 350k mails by now (accumulated over the last three years) and most email clients are tried don't work with such numbers very well. Opera does an acceptable job, but every now and then it needs to update it local cache database, which can take ages. In case you wonder: I never delete any email (so that I can search them lateron, which I do every now and then)
I was wondering whether there's maybe an entirely different approach to mails. Something like Google Mail (does Google Mail work acceptably with ~500k mails?), but for the intranet. I have considered Horde IMP but I was told it's rather slow as well.
I suspect that some central SQL database with a reasonable web frontend might do the job for me, but I don't know any software which works like that.