The idea for this macro came from Dan, who is looking for a way to assign a category when a meeting is accepted.

I would like to change the color of a meeting once the invitee accepts the invitation. Looking at my calendar if the meeting is still the default color I'd know I need to follow up to ensure they're going to attend. Do you know of a way to do this?

You can do this using a variation of our Autoaccept a Meeting Request using Rules macro, using it with a Run a Script rule to look for accepted meeting responses and then add a category to the associated appointment.

This method can be used to change any field in the associated appointment. Remember, if you change the subject, location, or time, Outlook will need to send an update.

How to use this macro

Open Outlook's VBA editor (Alt+F11), right click on Project1 and choose Insert > Module. Paste the code into the module, then create the rule with the 'run a script' Action and select this script.

Complete steps for using the VBA Editor and SelfCert are at How to use the VBA Editor

Sub AcceptedMeetings(oRequest As MeetingItem)
If oRequest.MessageClass <> "IPM.Schedule.Meeting.Resp.Pos" Then
  Exit Sub
End If
 
Dim oAppt As AppointmentItem
Set oAppt = oRequest.GetAssociatedAppointment(True)
oAppt.Categories = "Green"
oAppt.Save

End Sub

Check for Declines

To categorize the meeting if any required attendee has declined, check for Declined responses then check the recipients list to see if any were required.

Sub CheckDeclines(oRequest As MeetingItem)
' only check declines
If oRequest.MessageClass <> "IPM.Schedule.Meeting.Resp.Neg" Then
  Exit Sub
End If
 
Dim oAppt As AppointmentItem
Set oAppt = oRequest.GetAssociatedAppointment(True)

Dim objAttendees As Outlook.Recipients
Dim objAttendeeReq As String
Set objAttendees = oAppt.Recipients

For x = 1 To objAttendees.Count
   If objAttendees(x).Type = olRequired Then
    oAppt.Categories = "Declined;" & oAppt.Categories
   End If
Next
oAppt.Save

End Sub

Add Categories for Specific Attendees

To add a category based on the accepted recipients, use this script to check the recipient lists. This sets a category only if specific required attendees accept. As written, it uses their name as the category, but you can use a specific category (such as "Accepted") instead.

To use this to add a category named for each accepted attendees, move oAppt.Categories = objAttendeeReq & ";" & oAppt.Categories right after objAttendeeReq = objAttendees(x).Address and remove the lines following the first End If down to the last Next.

You can use attendee names or their email addresses, but the email address is generally more accurate for Internet addresses while the display name will work better for coworkers on Exchange server. You can check for the address then use the display name as the category.

Sub CategorizeMeetings(oRequest As MeetingItem)
If oRequest.MessageClass <> "IPM.Schedule.Meeting.Resp.Pos" Then
  Exit Sub
End If
 
Dim oAppt As AppointmentItem
Set oAppt = oRequest.GetAssociatedAppointment(True)

Dim objAttendees As Outlook.Recipients
Dim objAttendeeReq As String
Set objAttendees = oAppt.Recipients

For x = 1 To objAttendees.Count
   If objAttendees(x).Type = olRequired Then
      'objAttendeeReq = objAttendees(x).Name
      objAttendeeReq = objAttendees(x).Address
   End If
' Set up the array to check for specific people
arrRequired = Array("Diane Poremsky", "alias@domain.com", "diane@domain.com")

' Go through the array and look for a match, then do something
For i = LBound(arrRequired) To UBound(arrRequired)
    If InStr(LCase(objAttendeeReq), arrRequired(i)) Then
 ' new cat first
   oAppt.Categories = objAttendeeReq & ";" & oAppt.Categories
End If

Next i
Next

oAppt.Save

End Sub

To use these macros with declined or tentative responses, change the message class to one of the following message classes: