The first error sounds like your configured mail server does not allow relaying. You may want to adjust the settings in episervermail.config.

Regarding the second error it sounds like the result of a known issue with the Community integration in the original 4.4 release (I guess this is what you have?). The easiest way to solve that would be to install the 4.4 SP1.

I've managed to solve the smtp-problem, tho when I upgraded an to SP1 I Get the Following error on every page (New mailing, sent mailing etc.)

 Server Error in '/' Application.
Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
EPiServer.Mail.Core.Web.SentMailControl.Page_Init(Object sender, EventArgs e) +38
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
System.Web.UI.Control.OnInit(EventArgs e) +99
System.Web.UI.UserControl.OnInit(EventArgs e) +77
EPiServer.Mail.Core.Web.SentMailControl.OnInit(EventArgs e) +25
System.Web.UI.Control.InitRecursive(Control namingContainer) +333
System.Web.UI.Control.AddedControl(Control control, Int32 index) +198
System.Web.UI.ControlCollection.Add(Control child) +80
EPiServer.Mail.Core.Web.ControlWrapper.Page_Load(Object sender, EventArgs e) +131
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
System.Web.UI.Control.OnLoad(EventArgs e) +99
System.Web.UI.Control.LoadRecursive() +50
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627


Version Information: Microsoft .NET Framework Version:2.0.50727.4016; ASP.NET Version:2.0.50727.4016