Agreed, I have looked at both Zimbra and Scalix for collaborative functions - ZImbra has the better features, and Scalix installs better on exiting platforms. I am tempted by OpenGoo for their current and forthcoming document collaboration features, but their email app needs some work.
As someone that has to use Scalix as the LEA implementation I would avoid it, we do not have a good time with it. It may be due to poor implementation perhaps by the LEA but the concepts behind it that we see and use make it look like say Windows 3.1 VS XP Pro we all would probably have XP Pro for its features, usability etc. Fine Scalix is email but just seems so out of date and old.
Why not change provider of ADSL or move to bonded adsl form a buiness provider? You could always host your server in a co-lo.
We are using Google Apps for education for the last two years. I do not see any problem in using it at all. We have only once down time for an hour when the google mail was down in the world. Apart from that we do not have any problem. Currently it supports 1250 users free of cost. We do not need anymore so did not ask for it.
I think google apps is the best solution for up to 7GB of mail boxes. In the time when everybody is depending on email for communication we should go for something reliable not like restarting server every day or week.
We've been using Google Apps for nearly a year now, used to be on RM Easymail. Initially there were a few issues with some members of staff accidentally deleting their emails as they though that gmail labels were the samething as folders - so they would label something and then delete it instead of archiving it.
You get 66% discount on postini security and filtering products too as long as your grand total bill for the year is over £2000, which doesn't sound that cheap but actually compares well to other services with filtering and 7GB of storage.
Performance wise it'd only ever been down a couple of times and it always seems to be going a decent speed. I really like it. The best bit is that it has directory sync and SSO funcationality built into the educational version so if your backend structure is nicely organised you could get something that is effectively zero maintenace.
I was really interested in Microsofts Live@Edu as well, but for full integration with AD I think you need to invest in MS server products whereas Google was free to try out all the functionailty. Maybe the Microsoft solution would have tighter and smarter integration though.
The main issue so far has been setting up other applications and utilities that expect an onsite SMTP server, we are currently investigating a hosted offsite relay as SWGFL block direct access to smtp.gmail.com, we had it working intermitantly for a few months but it seems more reliable to relay the mail first rather than go straight to gmail servers.