I've looked at replacing our exchange box at work as well.. (150 mailboxes, over 10Gig of mail, turns over 30,000 messages a month)
I decided not to do so after a lot of soul searching, and testing with other options, it may be a lump of junk in some respects but it is probably the best integrated tool in that market space, and with our government select agreement the cost is academic. Some comments inserted.. > Exchange is a festering heap of fertilliser. There is no way to move > all the existing mail from ES to any other mailserver other than > forwarding all email manually. Not at a server level, but you can create a PST for the user, copy the mail, connect to new IMAP server, copy mail back.... If you export from the root of the mailbox down it will also keep their contacts, and you can just put the mail on the Linux Imap server, and keep the contacts in a PST their Local drive. Assuming roaming profiles they'll hardly notice the difference. This is not a problem unique to Exchange though, moving between any proprietary (and some open source) mail server solutions is a manual process, you just need to decide how much manual is too much :-). > We have made a partial change - I run squirrelmail on the webserver > (linux) which is a webmail/imap gateway, and that runs fairly well. Have you got squirrel talking to the Exchange IMAP? I tried this out a while ago and didn't get very far, but then got sidetracked and didn't get back to it. It'd be handy to have a light-weight option for webmail to bolt onto the mail server... > Users will loose all the calendaring/schedualling/addressbook components > of exchange server too, when you change to something else. If you're using Outlook 2k as a client you can get all of the scheduling to work using the vcalendar support on a linux box using ftp & http, and the global address book can be replaced with LDAP. There are some how-to's on the web for this, I found a good one in french that bablefish translated well enough for me to test it out. Yes, I know, outlook is evil and all that, but it's a good mail client (not ignoring the fact that Outlook is the biggest security hole in history) > But then - its impossible to restore a single email from a tape > backup... you have to restore the lot to a scratch machine then forward > it to the real server, so I have always told users to save important > emails to disk. ? A decent Brick-level backup gives you this, get a new backup product... Or forward all emails to a single archive mailbox (Option Buried in the server setup somewhere).. I'm not defending MS, but this is one of the most common gripes about Exchange, but doesn't need to the the case. > You might have to bite the bull's horns and change wholesale, loosing > the old mail... which is going to be a real turn-off for users. Now there's a good career move :-). How much mail have you got to carry over? If it's not a lot the courier/cyrus + LDAP + Vcalendar is definitely worth looking at, as then you can chuck out your CAL's for exchange, and if you're not running any other MS dependant services you can drop your server CAL's as well, and use Samba as your PDC. In that sense loosing exchange is the key to massive cost savings for some sites.. Cheers, Chris H.