Answer a collection of emails in a batch using Outlook

"The quickest way I can think of is an outlook vba macro, provided you don't mind Outlook throwing a bit of a tantrum that you're automating it - it'll warn you that it might be a virus.

Something like the following

Public Sub test()
Dim ns As NameSpace
Set ns = Application.GetNamespace(""MAPI"")
Dim outlookFolder As Object, innerFolder As MAPIFolder
Set outlookFolder = ns.Folders(""Mailbox - Your mailbox name"")
Debug.Print outlookFolder.Name
Set innerFolder = outlookFolder.Folders(""Inbox"")
Debug.Print vbTab & innerFolder.Name
Dim emailItem As MailItem
For Each emailItem In innerFolder.Items
If emailItem.Subject = ""Test"" Then
Dim replyEmail As MailItem
Set replyEmail = emailItem.Reply
replyEmail.Body = ""Test 2""
replyEmail.Display
replyEmail.Send
End If

Next it
End Sub

So for the above, for each email it finds in your inbox with the subject ""Test"", it'll send a reply to the original sender with the body ""Test 2""."