这就是 Outlook 2019 对我有用的方法。使用您的内部域名。可能还需要一些调整 - 没有经过大量测试。将代码放在 ThisOutlookSession 模块中。(已于 2020 年 7 月 31 日更新以处理 Exchange 分发列表。)
Private Sub Application_ItemSend(ByVal Item As Object, Cancel As Boolean)
Dim xMailItem As Outlook.MailItem
Dim xRecipients As Outlook.Recipients
Dim OutRec As Outlook.Recipient
Dim OutTI As Outlook.TaskItem
Dim i As Long
Dim j As Long
Dim xOKCancel As Integer
Dim sMsg As String
Dim oMembers As AddressEntries
Dim oMember As AddressEntry
Dim sDomains As String
Dim sTemp As String
On Error Resume Next
If Item.Class <> olMail Then GoTo ExitCode
sDomains = "@test1.com @test2.com"
Set xMailItem = Item
Set xRecipients = xMailItem.Recipients
'Loop through email recipients to get email addresses
For i = xRecipients.Count To 1 Step -1
'If we have a text address entry in the email
If InStr(xRecipients.Item(i).AddressEntry, "@") > 0 Then
sTemp = xRecipients.Item(i).AddressEntry
If InStrRev(sDomains, LCase(Mid(sTemp, InStr(sTemp, "@"), 254))) <= 0 Then
sMsg = sMsg & sTemp & vbCrLf
End If
Else
Select Case xRecipients.Item(i).AddressEntry.DisplayType
Case Is = olDistList
Set oMembers = xRecipients.Item(i).AddressEntry.Members
For j = oMembers.Count To 1 Step -1
Set oMember = oMembers.Item(j)
sTemp = oMember.GetExchangeUser.PrimarySmtpAddress
If InStrRev(sDomains, LCase(Mid(sTemp, InStr(sTemp, "@"), 254))) <= 0 Then
sMsg = sMsg & sTemp & vbCrLf
End If
Set oMember = Nothing
Next j
Set oMembers = Nothing
Case Is = olUser
Set OutTI = Application.CreateItem(3)
OutTI.Assign
Set OutRec = OutTI.Recipients.Add(xRecipients.Item(i).AddressEntry)
OutRec.Resolve
If OutRec.Resolved Then
sTemp = OutRec.AddressEntry.GetExchangeUser.PrimarySmtpAddress
If InStrRev(sDomains, LCase(Mid(sTemp, InStr(sTemp, "@"), 254))) <= 0 Then
sMsg = sMsg & sTemp & vbCrLf
End If
End If
Set OutTI = Nothing
Set OutRec = Nothing
Case Else
MsgBox "Unaccomodated AddressEntry.DisplayType."
GoTo ExitCode
End Select
End If
Next i
'Display user message
If Len(sMsg) > 0 Then
sMsg = "This email is addressed to the following external Recipients:" & vbCrLf & vbCrLf & sMsg
xOKCancel = MsgBox(sMsg, vbOKCancel + vbQuestion, "Warning")
If xOKCancel = vbCancel Then Cancel = True
End If
End Sub