I’m often asked how to be reminded if a message does not arrive within a specified time. This a popular request by administrators and others who receive routine status messages. When a status message doesn't arrive, it can mean there is a problem.

Is it possible to set a reminder, or email myself automatically, if a particular email does not arrive by a certain time every hour?

Yes, you can do this using a run a script rule. Outlook doesn't have a timer, so you'll need to use reminders to trigger the check. When a message arrives, a reminder is set for one hour and the reminder and flag are removed from the older message(s). If you prefer, you can delete the older message instead.

While this code sample only triggers a reminder, you can use the method described at Send an email when an Appointment reminder fires to send an email when the reminder fires.

To use, add this code to a new module in Outlook's VBA Editor and create a run a script rule.

Sub RemindNewMessages(Item As Outlook.MailItem)
 
Dim objInbox As Outlook.MAPIFolder
Dim intCount As Integer
Dim objVariant As Variant
 
Set objInbox = Session.GetDefaultFolder(olFolderInbox)
 
' Set the flag/reminder on newly arrived message
 With Item
    .MarkAsTask olMarkThisWeek
    .TaskDueDate = Now + 1
    .ReminderSet = True
    ' Reminder in one hour
    .ReminderTime = Now + 0.041
    .Categories = "Remind in 1 Hour"
    .Save
End With

Item.Save
 
' look for existing messages and remove the flag and reminder 
For intCount = objInbox.Items.Count To 1 Step -1
 Set objVariant = objInbox.Items.Item(intCount)
 
 If objVariant.MessageClass = "IPM.Note" Then
    If LCase(objVariant.Subject) = LCase(Item.Subject) And objVariant.SentOn < Item.SentOn Then
' clear flag and category
With objVariant
    .ClearTaskFlag
    .Categories = ""
    .Save
End With

'or just delete the older messages
   '  objVariant.Delete
     Else
    End If
 End If
Next
 
Set objInbox = Nothing
End Sub

Use an ItemAdd macro to watch a shared mailbox

This version of the macro uses an ItemAdd macro to watch the inbox in a shared mailbox. The shared mailbox needs to be in your profile for this to work.

It checks every message that arrives, you'll need to use an If statement if you want to check only certain messages.

Option Explicit
Private objNS As Outlook.NameSpace
Private WithEvents objNewMailItems As Outlook.Items
Private objInbox As Outlook.MAPIFolder

Private Sub Application_Startup()
Dim objOwner As Outlook.Recipient
Set objNS = Application.GetNamespace("MAPI")

 Set objOwner = objNS.CreateRecipient("chris")
   objOwner.Resolve
If objOwner.Resolved Then
Set objInbox = objNS.GetSharedDefaultFolder(objOwner, olFolderInbox)
End If

Set objNewMailItems = objInbox.Items
End Sub

Sub objNewMailItems_ItemAdd(ByVal Item As Object)

Dim intCount As Integer
Dim objVariant As Variant
   
' Set the flag/reminder on newly arrived message
 With Item
    .MarkAsTask olMarkThisWeek
  '  .TaskDueDate = Now + 1
    .ReminderSet = True
    ' Reminder in one hour
    .ReminderTime = Now + 0.041
    .Categories = "Remind in 1 Hour"
    .Save
End With
 
Item.Save
  
' look for existing messages and remove the flag and reminder
For intCount = objInbox.Items.Count To 1 Step -1
 Set objVariant = objInbox.Items.Item(intCount)
  
 If objVariant.MessageClass = "IPM.Note" Then
    If LCase(objVariant.Subject) = LCase(Item.Subject) And objVariant.SentOn < Item.SentOn Then
' clear flag and category
With objVariant
    .ClearTaskFlag
    .Categories = ""
    .Save
End With
 
'or just delete the older messages
   '  objVariant.Delete
     Else
    End If
 End If
Next
End Sub

How to use macros

First: You will need macro security set to low during testing.

To check your macro security in Outlook 2010 or 2013, go to File, Options, Trust Center and open Trust Center Settings, and change the Macro Settings. In Outlook 2007 and older, it’s at Tools, Macro Security.

After you test the macro and see that it works, you can either leave macro security set to low or sign the macro.

Open the VBA Editor by pressing Alt+F11 on your keyboard.

To put the code in a module:

1. Right click on Project1 and choose Insert > Module
2. Copy and paste the macro into the new module.

More information as well as screenshots are at How to use the VBA Editor