Mandatory Feild on Web Form

Good Afternoon

Is it possible to make the email feild mandatory, with the form not sending until this feild has been completed?

Thank you

]<br />
<td><font face="Arial" color="#000000"><label for="sendto">Support Team</label></td><td><select  id="sendto" name="sendto"><option>Please select one</option>
<option value="sales">Sales</option>
<option value="training">Training</option>
<option value="service">Service</option>
<option value="general">General</option>
</select></td>
</tr>
<tr>
<td><font face="Arial" color="#000000"><label for="name">Name</label></td><td><input type="text" id="name" name="fullname" /></td>
	</tr>
	<tr>
<td><font face="Arial" color="#000000"><label for="email">Email</label></td><td><input type="text" id="email" name="email" /></td>
	</tr>
	<tr>
<td><font face="Arial" color="#000000"><label for="subject">Subject</label></td><td><input type="text" id="subject" name="subject" /></td>
	</tr>
	<tr>
<td><font face="Arial" color="#000000"><label for="message">Message</label></td><td><textarea cols="50" rows="4" name="message"></textarea></td>	
</tr>
</table>
</br>
</br>
<input type="submit" >
</br>

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