Q:

Facelet get object attribute

I try to print the name of the logged user this way:
<p>Welcome #{sessionScope.authUser.email}</p>

In the User model the get-er and set-er for the name are present. 
This is the error thrown:
javax.servlet. ServletException: For input string: "email"

What am I doing wrong? 
EDIT Stack trace:
SEVERE: Error Rendering View[/account.xhtml]
javax.el. ELException: /account.xhtml: For input string: "email"
    at com.sun.faces.facelets.compiler. TextInstruction.write(TextInstruction.java:90)
    at com.sun.faces.facelets.compiler. UIInstructions.encodeBegin(UIInstructions.java:82)
    at com.sun.faces.facelets.compiler. UILeaf.encodeAll(UILeaf.java:183)
    at javax.faces.component. UIComponent.encodeAll(UIComponent.java:1759)
    at javax.faces.component. UIComponent.encodeAll(UIComponent.java:1759)
    at com.sun.faces.application.view. FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:401)
    at com.sun.faces.application.view. MultiViewHandler.renderView(MultiViewHandler.java:131)
    at com.sun.faces.lifecycle. RenderResponsePhase.execute(RenderResponsePhase.java:121)
    at com.sun.faces.lifecycle. Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle. LifecycleImpl.render(LifecycleImpl.java:139)
    at javax.faces.webapp. FacesServlet.service(FacesServlet.java:594)
    at org.apache.catalina.core. StandardWrapper.service(StandardWrapper.java:1539)
    at org.apache.catalina.core. StandardWrapperValve.invoke(StandardWrapperValve.java:281)
    at org.apache.catalina.core. StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core. StandardPipeline.doInvoke(StandardPipeline.java:655)
    at org.apache.catalina.core. StandardPipeline.invoke(StandardPipeline.java:595)
    at com.sun.enterprise.web. WebPipeline.invoke(WebPipeline.java:98)
    at com.sun.enterprise.web. PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
    at org.apache.catalina.core. StandardHostValve.invoke(StandardHostValve.java:162)
    at org.apache.catalina.connector. CoyoteAdapter.doService(CoyoteAdapter.java:330)
    at org.apache.catalina.connector. CoyoteAdapter.service(CoyoteAdapter.java:231)
    at com.sun.enterprise.v3.services.impl. ContainerMapper.service(ContainerMapper.java:174)
    at com.sun.grizzly.http. ProcessorTask.invokeAdapter(ProcessorTask.java:828)
    at com.sun.grizzly.http. ProcessorTask.doProcess(ProcessorTask.java:725)
    at com.sun.grizzly.http. ProcessorTask.process(ProcessorTask.java:1019)
    at com.sun.grizzly.http. DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
    at com.sun.grizzly. DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly. DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly. DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http. HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly. ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly. SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly. ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util. AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util. AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang. Thread.run(Thread.java:662)
Caused by: java.lang. NumberFormatException: For input string: "email"
    at java.lang. NumberFormatException.forInputString(NumberFormatException.java:48)
    at java.lang. Integer.parseInt(Integer.java:449)
    at java.lang. Integer.parseInt(Integer.java:499)
    at javax.el. ListELResolver.toInteger(ListELResolver.java:407)
    at javax.el. ListELResolver.getValue(ListELResolver.java:199)
    at com.sun.faces.el. DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
    at com.sun.faces.el. DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
    at com.sun.el.parser. AstValue.getValue(AstValue.java:116)
    at com.sun.el.parser. AstValue.getValue(AstValue.java:163)
    at com.sun.el. ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
    at com.sun.faces.facelets.el. ELText$ELTextVariable.writeText(ELText.java:224)
    at com.sun.faces.facelets.el. ELText$ELTextComposite.writeText(ELText.java:148)
    at com.sun.faces.facelets.compiler. TextInstruction.write(TextInstruction.java:85)
    ... 35 more

INFO: Exit : render_response 6
WARNING: StandardWrapperValve[Faces Servlet]: PWC1406: Servlet.service() for servlet Faces Servlet threw exception
java.lang. NumberFormatException: For input string: "email"
    at java.lang. NumberFormatException.forInputString(NumberFormatException.java:48)
    at java.lang. Integer.parseInt(Integer.java:449)
    at java.lang. Integer.parseInt(Integer.java:499)
    at javax.el. ListELResolver.toInteger(ListELResolver.java:407)
    at javax.el. ListELResolver.getValue(ListELResolver.java:199)
    at com.sun.faces.el. DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
    at com.sun.faces.el. DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
    at com.sun.el.parser. AstValue.getValue(AstValue.java:116)
    at com.sun.el.parser. AstValue.getValue(AstValue.java:163)
    at com.sun.el. ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
    at com.sun.faces.facelets.el. ELText$ELTextVariable.writeText(ELText.java:224)
    at com.sun.faces.facelets.el. ELText$ELTextComposite.writeText(ELText.java:148)
    at com.sun.faces.facelets.compiler. TextInstruction.write(TextInstruction.java:85)
    at com.sun.faces.facelets.compiler. UIInstructions.encodeBegin(UIInstructions.java:82)
    at com.sun.faces.facelets.compiler. UILeaf.encodeAll(UILeaf.java:183)
    at javax.faces.component. UIComponent.encodeAll(UIComponent.java:1759)
    at javax.faces.component. UIComponent.encodeAll(UIComponent.java:1759)
    at com.sun.faces.application.view. FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:401)
    at com.sun.faces.application.view. MultiViewHandler.renderView(MultiViewHandler.java:131)
    at com.sun.faces.lifecycle. RenderResponsePhase.execute(RenderResponsePhase.java:121)
    at com.sun.faces.lifecycle. Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle. LifecycleImpl.render(LifecycleImpl.java:139)
    at javax.faces.webapp. FacesServlet.service(FacesServlet.java:594)
    at org.apache.catalina.core. StandardWrapper.service(StandardWrapper.java:1539)
    at org.apache.catalina.core. StandardWrapperValve.invoke(StandardWrapperValve.java:281)
    at org.apache.catalina.core. StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core. StandardPipeline.doInvoke(StandardPipeline.java:655)
    at org.apache.catalina.core. StandardPipeline.invoke(StandardPipeline.java:595)
    at com.sun.enterprise.web. WebPipeline.invoke(WebPipeline.java:98)
    at com.sun.enterprise.web. PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
    at org.apache.catalina.core. StandardHostValve.invoke(StandardHostValve.java:162)
    at org.apache.catalina.connector. CoyoteAdapter.doService(CoyoteAdapter.java:330)
    at org.apache.catalina.connector. CoyoteAdapter.service(CoyoteAdapter.java:231)
    at com.sun.enterprise.v3.services.impl. ContainerMapper.service(ContainerMapper.java:174)
    at com.sun.grizzly.http. ProcessorTask.invokeAdapter(ProcessorTask.java:828)
    at com.sun.grizzly.http. ProcessorTask.doProcess(ProcessorTask.java:725)
    at com.sun.grizzly.http. ProcessorTask.process(ProcessorTask.java:1019)
    at com.sun.grizzly.http. DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
    at com.sun.grizzly. DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly. DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly. DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http. HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly. ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly. SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly. ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util. AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util. AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang. Thread.run(Thread.java:662)

A:

<p>Welcome #{sessionScope.authUser.name}</p>

That line of code can impossibly have thrown this exception. 
java.lang. NumberFormatException: For input string: "email"
    at java.lang. NumberFormatException.forInputString(NumberFormatException.java:48)
    at java.lang. Integer.parseInt(Integer.java:449)
    at java.lang. Integer.parseInt(Integer.java:499)
    at javax.el. ListELResolver.toInteger(ListELResolver.java:407)
    at javax.el. ListELResolver.getValue(ListELResolver.java:199)
    at com.sun.faces.el. DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
    at com.sun.faces.el. DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
    at com.sun.el.parser. AstValue.getValue(AstValue.java:116)
    at com.sun.el.parser. AstValue.getValue(AstValue.java:163)
    at com.sun.el. ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
    ...

Look, there's a ListELResolver involved.  This suggests that you have somewhere something like a 
#{bean.list.email}

where #{bean.list} actually returns a List and thus needs to be accessed by an integer index using the brace notation [] like as follows to get the 1st item (which in turn of course should have the email property):
#{bean.list[0].email}

Update as per your update, the real code is
<p>Welcome #{sessionScope.authUser.email}</p>

The authUser apparently implements List or extends one of its subclasses.  This makes no sense for a managed bean.  Remove the interface or the subclass from the managed bean class declaration.  Just the following is sufficient:
@ManagedBean
@SessionScoped
public class AuthUser implements Serializable {
    // ...
}

Also, although explicitly specifying the scope like as in #{sessionScope.authUser} may be helpful for self-documentary purposes, this is unnecessary.  Just use #{authUser}. 

Update 2 as per the comments: you seem to have manually placed an object in the session scope which is actually a List.  This is fishy.  Consider using a normal session scoped managed bean which you inject as a managed property in a request scoped bean which handles the login.