@bardev提供了一个很好的解决方案，但是不幸的是，它并非在所有情况下都是理想的。我的就是其中之一。
我在VS 2013中在网站中使用WebForms（我发誓我永远不会再使用网站-PITA）。
我尝试了Razor的建议，但是作为一个网站，我没有得到IDE在MVC项目中提供的最重要的IntelliSense。我还喜欢将设计器用于模板，这是UserControl的理想之地。
尼克斯再次剃刀。
所以我想出了这个小框架（对于UserControl，@ mun表示技巧，对于强类型，@ imatoria表示技巧）。我几乎可以看到的唯一潜在问题是，您必须注意保持.ASCX文件名与其类名同步。如果您迷路了，则会遇到运行时错误。
FWIW：在我的测试中，至少RenderControl（）调用不喜欢Page控件，因此我使用了UserControl。
我很确定我已经将所有内容都包括在内了；让我知道是否遗漏了一些东西。
高温超导
用法：
Partial Class Purchase
Inherits UserControl
Private Sub SendReceipt()
Dim oTemplate As MailTemplates.PurchaseReceipt
oTemplate = MailTemplates.Templates.PurchaseReceipt(Me)
oTemplate.Name = "James Bond"
oTemplate.OrderTotal = 3500000
oTemplate.OrderDescription = "Q-Stuff"
oTemplate.InjectCss("PurchaseReceipt")
Utils.SendMail("{0} <james.bond@mi6.co.uk>".ToFormat(oTemplate.Name), "Purchase Receipt", oTemplate.ToHtml)
End Sub
End Class
基类：
Namespace MailTemplates
Public MustInherit Class BaseTemplate
Inherits UserControl
Public Shared Function GetTemplate(Caller As TemplateControl, Template As Type) As BaseTemplate
Return Caller.LoadControl("~/MailTemplates/{0}.ascx".ToFormat(Template.Name))
End Function
Public Sub InjectCss(FileName As String)
If Me.Styler IsNot Nothing Then
Me.Styler.Controls.Add(New Controls.Styler(FileName))
End If
End Sub
Private ReadOnly Property Styler As PlaceHolder
Get
If _Styler Is Nothing Then
_Styler = Me.FindNestedControl(GetType(PlaceHolder))
End If
Return _Styler
End Get
End Property
Private _Styler As PlaceHolder
End Class
End Namespace
“工厂”类别：
Namespace MailTemplates
Public Class Templates
Public Shared ReadOnly Property PurchaseReceipt(Caller As TemplateControl) As PurchaseReceipt
Get
Return BaseTemplate.GetTemplate(Caller, GetType(PurchaseReceipt))
End Get
End Property
End Class
End Namespace
模板类别：
Namespace MailTemplates
Public MustInherit Class PurchaseReceipt
Inherits BaseTemplate
Public MustOverride WriteOnly Property Name As String
Public MustOverride WriteOnly Property OrderTotal As Decimal
Public MustOverride WriteOnly Property OrderDescription As String
End Class
End Namespace
ASCX标头：
<%@ Control Language="VB" ClassName="_Header" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional //EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<!--
See https://www.campaignmonitor.com/blog/post/3317/ for discussion of DocType in HTML Email
-->
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<asp:PlaceHolder ID="plcStyler" runat="server"></asp:PlaceHolder>
</head>
<body>
ASCX页脚：
<%@ Control Language="VB" ClassName="_Footer" %>
</body>
</html>
ASCX模板：
<%@ Control Language="VB" AutoEventWireup="false" CodeFile="PurchaseReceipt.ascx.vb" Inherits="PurchaseReceipt" %>
<%@ Register Src="_Header.ascx" TagName="Header" TagPrefix="uc" %>
<%@ Register Src="_Footer.ascx" TagName="Footer" TagPrefix="uc" %>
<uc:Header ID="ctlHeader" runat="server" />
<p>Name: <asp:Label ID="lblName" runat="server"></asp:Label></p>
<p>Order Total: <asp:Label ID="lblOrderTotal" runat="server"></asp:Label></p>
<p>Order Description: <asp:Label ID="lblOrderDescription" runat="server"></asp:Label></p>
<uc:Footer ID="ctlFooter" runat="server" />
ASCX模板代码文件：
Partial Class PurchaseReceipt
Inherits MailTemplates.PurchaseReceipt
Public Overrides WriteOnly Property Name As String
Set(Value As String)
lblName.Text = Value
End Set
End Property
Public Overrides WriteOnly Property OrderTotal As Decimal
Set(Value As Boolean)
lblOrderTotal.Text = Value
End Set
End Property
Public Overrides WriteOnly Property OrderDescription As Decimal
Set(Value As Boolean)
lblOrderDescription.Text = Value
End Set
End Property
End Class
帮手：
'
' FindNestedControl helpers based on tip by @andleer
' at http://stackoverflow.com/questions/619449/
'
Public Module Helpers
<Extension>
Public Function AllControls(Control As Control) As List(Of Control)
Return Control.Controls.Flatten
End Function
<Extension>
Public Function FindNestedControl(Control As Control, Id As String) As Control
Return Control.Controls.Flatten(Function(C) C.ID = Id).SingleOrDefault
End Function
<Extension>
Public Function FindNestedControl(Control As Control, Type As Type) As Control
Return Control.Controls.Flatten(Function(C) C.GetType = Type).SingleOrDefault
End Function
<Extension>
Public Function Flatten(Controls As ControlCollection) As List(Of Control)
Flatten = New List(Of Control)
Controls.Traverse(Sub(Control) Flatten.Add(Control))
End Function
<Extension>
Public Function Flatten(Controls As ControlCollection, Predicate As Func(Of Control, Boolean)) As List(Of Control)
Flatten = New List(Of Control)
Controls.Traverse(Sub(Control)
If Predicate(Control) Then
Flatten.Add(Control)
End If
End Sub)
End Function
<Extension>
Public Sub Traverse(Controls As ControlCollection, Action As Action(Of Control))
Controls.Cast(Of Control).ToList.ForEach(Sub(Control As Control)
Action(Control)
If Control.HasControls Then
Control.Controls.Traverse(Action)
End If
End Sub)
End Sub
<Extension()>
Public Function ToFormat(Template As String, ParamArray Values As Object()) As String
Return String.Format(Template, Values)
End Function
<Extension()>
Public Function ToHtml(Control As Control) As String
Dim oSb As StringBuilder
oSb = New StringBuilder
Using oSw As New StringWriter(oSb)
Using oTw As New HtmlTextWriter(oSw)
Control.RenderControl(oTw)
Return oSb.ToString
End Using
End Using
End Function
End Module
Namespace Controls
Public Class Styler
Inherits LiteralControl
Public Sub New(FileName As String)
Dim _
sFileName,
sFilePath As String
sFileName = Path.GetFileNameWithoutExtension(FileName)
sFilePath = HttpContext.Current.Server.MapPath("~/Styles/{0}.css".ToFormat(sFileName))
If File.Exists(sFilePath) Then
Me.Text = "{0}<style type=""text/css"">{0}{1}</style>{0}".ToFormat(vbCrLf, File.ReadAllText(sFilePath))
Else
Me.Text = String.Empty
End If
End Sub
End Class
End Namespace
Public Class Utils
Public Shared Sub SendMail(Recipient As MailAddress, Subject As String, HtmlBody As String)
Using oMessage As New MailMessage
oMessage.To.Add(Recipient)
oMessage.IsBodyHtml = True
oMessage.Subject = Subject.Trim
oMessage.Body = HtmlBody.Trim
Using oClient As New SmtpClient
oClient.Send(oMessage)
End Using
End Using
End Sub
End Class