Question

How can I achive the following?

    @foreach (var responsible in new List<string>{"receiver", "sender"})
    {
      <@responsible>
           ...
      </@responsible>
    }

Answer 1

The following should work:

@foreach (var responsible in new List<string>{"receiver", "sender"})
{
    @Html.Raw(string.Format("<{0}>", responsible))
        @:Hello world
    @Html.Raw(string.Format("</{0}>", responsible))
}

By the way if you are building XML with Razor please stop immediately and use a XML parser. For example write a custom Xml action result that will be passed your model and it will take care of generating it. Razor is meant for HTML, not anything else.