use match instead of srcip and use two rules
<rule id="100326" level="5">
<if_sid>xxxx</if_sid>
<srcip>XXX.XXX.XXX.XXX</srcip>
<description>Suppress Alerts from Server</description>
</rule>
<rule id="100327" level="5" >
<if_sid>xxxx</if_sid>
<match>server1</match>
<description>Suppress Alerts from Server</description>
</rule>
