VSTO & .NET & Excel

April 27, 2010

VSTO: Automate MS Outlook in Excel using Template

Filed under: .NET & Excel, Excel, VSTO & Excel — Dennis M Wallentin @ 5:14 pm

In Office Automation one of the cornestones, at least for me, is templates. Using templates in Excel, in Word and in Outlook creates value as they provide us with tools to customize documents and doing so gives us structural solutions that can be applied inside corporates. Personally I find it to be excellent whenever I can use templates as part of solutions.

Here I will demonstrate how we can use a template for e-mails and how we can automate MS Outlook from Excel in a VSTO solution. The VSTO solution is created with Add-in Express 2009 For Microsoft Office and VSTO which is my #1 tool as it makes deployment so easy and smooth.

Part One: Creating the Outlook Template
Creating an e-mail template is very easy as we first create a new e-mail, add the wanted formatting and finally save it as a template.

The following screen shot shows the e-mail template that will be used:

After we have created the template we save it which the below screen shot also shows:

Part Two: Automate Outlook and use the template to create an e-mail
For our solution I have created a Ribbon solution where the Report button DZ-22A is available under the tab Add-ins which also the following screen shot shows:

When automation Outlook from Excel and other programs we need to pay attention to the fact that there can only be one running instance of Outlook. In order to avoid that we create a new window for Outlook whenever the code is executed we need to hook into the instance whenever Outlook is running. In other words, we need to check if Outlook is running or not. If running then we must hook into that instance and if not running we must create a new instance. The first part of the code solution checks the status and then take the appropriated action:

Imports Microsoft.Office.Tools.Ribbon
Imports Excel = Microsoft.Office.Interop.Excel
Imports Outlook = Microsoft.Office.Interop.Outlook
Imports System.Diagnostics
Imports System.Runtime.InteropServices
Imports System.Windows.Forms

Public Class MyRibbon

Dim m_olApp As Outlook.Application = Nothing
Dim m_olNamespace As Outlook.NameSpace = Nothing

Private Sub Button1_Click(ByVal sender As System.Object, _
ByVal e As  _
Microsoft.Office.Tools.Ribbon.RibbonControlEventArgs) _
Handles Button1.Click

If Is_Outlook_Running() Then

If Send_Mail_Attachment() Then
MessageBox.Show("The e-mail has successfully been created and sent.", _
"Sent Message", MessageBoxButtons.OK)
MessageBox.Show("An error occured while sending the e-mail.", "Send Error", _
End If


MessageBox.Show("Unable to establish a contact with MS Outlook!", _
"Fatal Error", MessageBoxButtons.OK)

End If

End Sub

Private Function Is_Outlook_Running() As Boolean

Dim Result As Boolean = Nothing
Dim canQuit As Boolean = Nothing


Dim Processes As Process() = Process.GetProcessesByName("OUTLOOK")
Dim CountLength As Integer = Processes.Length

If CountLength <> 0 Then
'Outlook is already running so we hook into the Outlook instance.
m_olApp = CType(Marshal.GetActiveObject("Outlook.Application"),  _
End If

If Not m_olApp Is Nothing Then
canQuit = False
'Outlook is not running so we instantiate a new session of Outlook.
m_olApp = New Outlook.Application
canQuit = True
End If

If Not m_olApp Is Nothing Then
If canQuit Then
m_olNamespace = m_olApp.GetNamespace("MAPI")
' Outlook is running so we just hook into existing session.
m_olNamespace = m_olApp.Session
End If
End If

Result = True

Catch e As Exception

m_olNamespace = Nothing
m_olApp = Nothing

Result = False

End Try

Return Result

End Function

In the second part of the code solution we create a new e-mail based on the template, manipulate some properties of the e-mail and then attach the active workbook. Finally we send the e-mail as the below function also shows:

Private Function Send_Mail_Attachment() As Boolean

Dim xlWorkbook As Excel.Workbook = _
Dim Result As Boolean = Nothing
Dim olNewMail As Outlook.MailItem = Nothing

Const Template As String = _
"C:\Users\Dennis\Documents\Automation\Weekly Report.oft"


olNewMail = CType(m_olApp.CreateItemFromTemplate(Template),  _

With olNewMail
If Not xlWorkbook.Saved Then xlWorkbook.Save()
.FlagStatus = Outlook.OlFlagStatus.olFlagMarked
.Importance = Outlook.OlImportance.olImportanceHigh
'If we want to display first and then manually send it.
End With

Result = True

Catch ex As Exception

Result = False


If Not m_olNamespace Is Nothing Then m_olNamespace = Nothing
If Not m_olApp Is Nothing Then m_olApp = Nothing

End Try

Return Result

End Function
End Class

Of course, when I come to think about; two other advantages with templates are that we don’t need to write code to format the documents and we can easily change them/replace them.

Kind regards,



  1. Wow, very impressive post Dennis. Reads very polished, like a chapter from a book… Is an Outlook book next? :-p

    I was wondering about checking whether Outlook is already running or not first. I had thought that with GlobalMultUse COM servers, like Outlook, that only one running instance can be created no matter what we do. So I think we can just create a “new” Outlook application, without checking first, and the object we get as a result is automatically either that of the already-running instance, or a new one, if none is already running.

    I’m not an Outlook programmer, so I’ve not tried, but one source I’ve seen is “Single-Use vs. Multi-Use Applications” (http://msdn.microsoft.com/en-us/library/aa164542(office.10).aspx). So the code can be shortened, which is nice.

    Great example, though, I can definitely see myself making use of this exact idea. Thanks for getting it started in a big way…

    – Mike

    Comment by Mike Rosenblum — April 28, 2010 @ 1:26 am

  2. Mike,

    Book? No, Outlook is not my favorite e-mail client. I have used PocoMail for the last 9-10 years.

    Anyway, what I should have explicit stated in the article is that when using the CreateObject(“Outlook.Application”) approach we are connected to the running instance of Outlook (as only one instance can exist). However, we are not connected to the Window of the running instance. So when using this approach we will always create a new window of the running Outlook instance.

    If we execute the code in this example and never do the check we will open a new Window each time it’s executed. This can be a potential end user issue as it always produces new Windows.

    Thanks for bringing it up so I got the chance to clarify it 🙂 Tomorrow the article will be updated accordingly.

    Who knows; perhaps it will be a contribution to a future Outlook book 😉

    Kind regards,

    Comment by Dennis Wallentin — April 28, 2010 @ 2:19 am

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