we find issue to our problem. we add content-disposition option on the attachment file property.

See the code below :

If Not strAttachments.Equals(String.Empty) Then

Dim strFile As String

Dim strAttach() As String = strAttachments.Split(";")

For Each strFile In strAttach

Dim Data As Net.Mail.Attachment = New Net.Mail.Attachment(strfile.trim())

Dim Disposition As Net.Mime.ContentDisposition = Data.ContentDisposition

Disposition.CreationDate = System.IO.File.GetCreationTime(strfile.trim())

Disposition.ModificationDate = System.IO.File.GetLastWriteTime(strfile.trim())

Disposition.ReadDate = System.IO.File.GetLastAccessTime(strfile.trim())

Mailmsg.Attachments.Add(Data)

Next

End If

It works well; so thanks a lot to everyone for help.

Very good article and very useful for us.

king regards