Thank you ruslan
According to you that I read post above and I do this I use the following rule for rewriting.
<rule name="Rewrite aspx" stopProcessing="false">
<match url="(.*).abcd" />
<action type="Rewrite" url="{R:1}.aspx" />
</rule>
Now I use a rule when the other user typed an address that ending with .aspx, must redirect to this address with the suffix .abcd.
<rule name="Redirect aspx" stopProcessing="true">
<match url="(.*).aspx" />
<action type="Redirect" url="{R:1}.abcd" redirectType="Permanent" />
</rule>
but I face Redirect Loop message. Please help me to.
Very Thank