Outlook and OSE pst problems

[traigo]

We currently have a small POP/SMTP/IMAP server and we've reached capacity. Spam filtering is no longer effective and it has become abondonware. We host our own email as well as the email for a few other small businesses and non-profits for free. We need to move to a more powerful server software with better spam prevention that is actively developed. One of our main problems is the 2gb PST issue with outlook. We have tried using IMAP, but searching is impossible and access to folders with >100 emails is dreadfully slow with our 768kbps up. What is the solution using the OSE?

Thanks,

Traigo