mail system

could you please suggest any mail system that met these requriments except horde and i recmonded if that can working under windows :
Dear Mr. Amin,
According to our phone conversation, please find below the requirements we need for a Mailing System:
1. Number of active mailboxes: 25.000.
2. Maillists (20.000) with automated generation.
3. POP3(s)/IMAP(s)/SMTP(s)
4. Webmail
5. Quota management
6. Management GUI
7. Comprehensive logging.
8. Mailbox migration from old system
9. Antivirus / Antispam / Keyword-based content filtering.
10. Users/maillists management API.
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BusbarSolutions ArchitectCommented:
why not using Exchange 2010, has it all
aminbaikAuthor Commented:
any other solution ?
aminbaikAuthor Commented:
Any other solution ?
How many server should i have?
i want to discuss as a full solutions.
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BusbarSolutions ArchitectCommented:
I will suggest to you to hire a consultant for that, full and accurate solution for such a volume cannot be discussed over the internet
aminbaikAuthor Commented:
what's the suggest infrustrcure to host 25000 mailbox account ?
BusbarSolutions ArchitectCommented:
it depends on their email usage roughly 4 servers 2 mailbox and 2 CAS, each with 64 GB of memory, 2 servers for AD and firewall.

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