If you want to set certain Outlook fields when you do a mail merge, you need to use an ItemSend rule.
To use, open the VBA Editor using Alt+F11 and expand Project1 until you see ThisOutlookSession. Double click on ThisOutlookSession and paste the macro in the right pane.
Change mail merge subject to match all or part of the subject, otherwise all mail you send will be marked important and have a reminder set. Change the reminder date and time.
Recipients may have rules to remove the reminder, flag, and Importance fields.
Private Sub Application_ItemSend(ByVal Item As Object, Cancel As Boolean) If InStr(LCase(Item.Subject), "mail merge subject") Then With Item .Importance = olImportanceHigh .ReminderSet = True .ReminderTime = #10/30/2012 8:00:00 AM# .FlagRequest = "Please reply by 10/30" ' to add an attachment, enter the path & name here .Attachments.Add "D:\For merge\filename.docx" End With End If End Sub
If you want to use a different attachment for each person, you'll need to use attachments that are the same name as a message field - the To field will probably be the easiest, although prone to problems. ("To" is the display name, not the email address.)
Item.Attachments.Add "D:\For merge\" & Item.To & ".docx"
Or use one of the utilities listed at Using Mail Merge in Outlook