IIS URL Rewrite except specific site - asp.net

Question

I have 3 sites (with different domains) which are hosted on one server, but all of them have same source and web.config. Sites 1 and 2 will be stopped and they should redirect to Site 4, but Site 3 will work as now...
I added a RewriteMap where described all pages redirects and a rule which is using that map:
<rewrite>
<rewriteMaps>
<rewriteMap name="My_RewriteMap" defaultValue="localhost/site4/Welcome.aspx">
<add key="/" value="localhost/site4/Welcome.aspx" />
<add key="/default.aspx" value="localhost/site4/Welcome.aspx" />
<add key="localhost/site2" value="localhost/site4/SpecificPage.aspx" />
<add key="/page3.aspx" value="localhost/site4/MyPage.aspx" />
<add key="new-page.aspx" value="localhost/site4/TheNewPage.aspx" />
...
</rewriteMap>
</rewriteMaps>
<rules>
<rule name="Redirect rule1 for My_RewriteMap" stopProcessing="true">
<match url=".*" negate="false" />
<conditions>
<add input="{My_RewriteMap:{REQUEST_URI}}" pattern="(.+)" />
</conditions>
<action type="Redirect" url="{C:1}" appendQueryString="false" />
</rule>
</rules>
</rewrite>
This code works for described pages in Map and for default value (if a specific page doesn't exist in the Map).
But this redirects Site 1, Site 2 and Site 3. I don't want to redirect to for Site3.
Is it possible with Rewrite URL feature?
I tried to edit match value with
<match url="localhost/Site3" negate="true" />
or
<match url="(localhost/Site3).*" negate="true" />
But both didn't work.
Thanks!

Answer 1

I Completed with next changes in conditions:
<conditions trackAllCaptures="true">
<add input="{HTTP_HOST}" pattern="localhost/Site3" negate="true" />
<add input="{My_RewriteMap:{REQUEST_URI}}" pattern="(.+)" />
</conditions>
With the first condition, I say to ignore all requests where Host (in {HTTP_HOST} variable) contains the site's domain: localhost/Site3.
Then, the second condition works for the Map.