You will need to make use of the Outlook Object Model DeferredDeliveryTime
property in a visual basic macro to do this.

The procedure will be something similar to that used in the article "Mail
Merge to E-mail with Attachments" at

http://word.mvps.org/FAQs/MailMerge/MergeWithAttachments.htm

I haven't tested this, but I think that the following modification (addition
of DeferredDeliveryTime = Now() + Format(1, "h")) to the routine in that
article would defer the sending of the emails by one hour.

   With oItem
       Set mysubject = Maillist.Tables(1).Cell(Counter, 2).Range
       mysubject.End = mysubject.End - 1
       .Subject = mysubject
       .Body = ActiveDocument.Content
       Set Datarange = Maillist.Tables(1).Cell(Counter, 1).Range
       Datarange.End = Datarange.End - 1
       .To = Datarange
       For i = 3 To Maillist.Tables(1).Columns.Count
           Set Datarange = Maillist.Tables(1).Cell(Counter, i).Range
           Datarange.End = Datarange.End - 1
           .Attachments.Add Trim(Datarange.Text), olByValue, 1
       Next i
       .Importance = olImportanceHigh
       .ReadReceiptRequested = True
       .Send
       .DeferredDeliveryTime = Now() + Format(1, "h")
   End With