Why pay for Zimbra.... get open source edition and have it up... and customize.. zimbra also is not that resource hungry... depends on your deployment and features you want.... which you can define as class of service. hence having optimized.<br>
<br>below are server requirement if you need zimbra with full email and collaboration features.<br><br><div class="CellBody"><a name="1063920">Production environments</a></div>
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                    <div class="CellBulleted_inner"><a name="1063921">Minimum - 32-bit OS with Intel/AMD 2.0 GHZ+ </a>CPU <br>Recommended - 64-bit OS </div>
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                    <div class="CellBulleted_inner"><a name="1063922">Minimum - 2 GB RAM</a><br>Recommend minimum - 4 GB RAM</div>
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                    <div class="CellBulleted_inner"><a name="1063923">Temp file space for installs and upgrades*</a></div>
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                    <div class="CellBulleted_inner"><a name="1063924">10 GB free disk space for software and logs (SATA </a>or SCSI for performance, and RAID/Mirroring for redundancy)</div>
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                    <div class="CellBulleted_inner"><a name="1063925">Additional disk space for mail storage</a><br></div>
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            <div class="CellBody"><a name="1063926">*Temp files space- The zimbra-store requires 5GB for /</a>opt/zimbra, plus additional space for mail storage. The other nodes require 100MB.</div>
            <div class="CellBody"><a name="1063927">General Requirements</a></div>
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                    <div class="CellBulleted_inner"><a name="1063928">Firewall Configuration should be set to “No </a>firewall”, and the Security Enhanced Linux (SELinux) should be disabled</div>
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                    <div class="CellBulleted_inner"><a name="1063929">RAID-5 is not recommended for installations with </a>more than 100 accounts.</div></td></tr></tbody></table><br>