Sometimes you want to send some important notice to everyone who
has ever mailed you. Let’s say you have a folder named “Friends” in
Outlook where you store all the emails from your friends. Now you
want to get all of their email addresses. Pretty difficult work if
you have thousands of such mails. Here’s an easy way.

• Select the folder in Outlook and press ALT+F11. It will open
  Visual Basic Editor.
• Double click on ThisOutlookSession from the Project tree.
• Paste the following function:

Sub GetALLEmailAddresses()

Dim objFolder As Folder
Set objFolder = Application.ActiveExplorer.Selection

Dim dic As New Dictionary
Dim strEmail As String
Dim strEmails As String

Dim objItem As MailItem
For Each objItem In objFolder.Items

strEmail = objItem.SenderEmailAddress
If Not dic.Exists(strEmail) Then
strEmails = strEmails + strEmail + “;”
dic.Add strEmail, “”
End If

Next

Debug.Print strEmails
End Sub

Hit F5 and it will run for a while. Then press Ctrl+G. You will
see the email addresses in the “Immediate
Window”.

Copy the whole string and you have all the email addresses from
all the emails in the selected Outlook folder. There will be no
duplicate address in the list.