mail using MAPI

Hi friends,

i have .dat file in which email ids are there separated by (. i want to sent an attachment to all of them could someone tell me how to go about it.

i tried to send attachment to one mailid but its not being sent. this is the code
Public Function send_mail(sendto As String, subject As String, filename As String, filepath As String) As Boolean
On Error GoTo ErrHandler
With MAPISession1
.DownLoadMail = False
.LogonUI = True
.SignOn
.NewSession = True
End With
With MAPIMessages1
.Compose
.RecipAddress = sendto
.AddressResolveUI = True
.ResolveName
.MsgSubject = subject
.AttachmentPathName = filepath
.Send True
End With
SendMail = True
ErrHandler:
End Function

Please if someone can help me out in this. i want for multiple mail ids.
Any help will be appreciated
thanx in advance.