Use font-awesome

interface/web/mail/templates/mail_user_mailbox_edit.htm

@@ -12,7 +12,7 @@
 							<select name="email_domain" id="email_domain" class="form-control" style="height:50px;min-width:170px;">{tmpl_var name='email_domain'}</select>
                         </div>
                         <a class="btn btn-default formbutton-narrow" href="javascript: navigator.clipboard.writeText(document.getElementById('email_local_part').value + '@' + document.getElementById('email_domain').value);" title="{tmpl_var name='copy_to_clipboard_txt'}">
-                            <span class="icon icon-bulb"></span>
+                            <span class="fa fa-clone"></span>
                         </a>
                     </div>
 				</div>

interface/web/sites/templates/shell_user_edit.htm

@@ -19,7 +19,7 @@
 						<span class="input-group-addon" id="username-desc">{tmpl_var name='username_prefix'}</span>
 						<input type="text" name="username" id="username" value="{tmpl_var name='username'}" class="form-control" aria-describedby="username-desc" style="width: 90%" />
 						<a class="btn btn-default formbutton-narrow" href="javascript: navigator.clipboard.writeText(document.getElementById('username-desc').innerText + document.getElementById('username').value);" title="{tmpl_var name='copy_to_clipboard_txt'}">
-							<span class="icon icon-bulb"></span>
+							<span class="fa fa-clone"></span>
 						</a>
 
 					</div>