Is there a way to perform validation for apex:inputField?

Hi Somendra,

You can add something like this:
1. Check the Empty
<apex:page id="page">

<script>
function show()
{
var name=document.getElementById('page:f1:p1:ip1').value;
if(name== "" || name==null)
{
document.getElementById("page:f1:p1:op2").innerHTML = "Please enter your name";
}
}
</script>

<apex:form id="f1">
<apex:pageblock id="p1">
<apex:outputlabel value="Enter u r name" id="op1" />
<apex:inputtext id="ip1" />
<apex:commandbutton value="submit" onclick="return show();" reRender="op2"/>
<apex:outputlabel id="op2" />
</apex:pageblock>
</apex:form>

</apex:page>

---> Besides salesforce has the on field validation, so u can have that option.

2. create formula syntax
Regression : '([a-zA-Z0-9_\-\.]+)@(((\[a-z]{1,3}\.[a-z]{1,3}\.[a-z]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3}))'