Ok, I found out how:

EPiServer.Web.Hosting.UnifiedFile uf = System.Web.Hosting.HostingEnvironment.VirtualPathProvider.GetFile(attachment) as EPiServer.Web.Hosting.UnifiedFile;

But the name of the attachmnet isn't the display name, is there anyway to change the name of the attachment in the mail.
 

Hi

 I'm not sure if this is what you are asking, but can't you do something like this:

UnifiedFile file = HostingEnvironment.VirtualPathProvider.GetFile(filePath) as UnifiedFile;

if (file != null)

{

using(Stream stream = file.Open())

{

string fileName = "My_file_name";

Attachment attachment = new Attachment(stream, fileName, "application/pdf"); //Or other Mime-type

//Send mail

}

}

Thanx for the tip it made me find the .Name attribute on the attachment and instead of using a strem a solved it like this:

//On page:
// -------- START Building attachment string
string attachmentFiles = "";
foreach (ListItem li in CheckBoxListFiles.Items)
{
 if (li.Selected == true)
 {
  attachmentFiles += li.Value + ";";
 }
}
if (attachmentFiles.Contains(";"))
{
 attachmentFiles = attachmentFiles.Substring(0, attachmentFiles.Length - 1);
}

string virtualFolder = FileDataSource.Root;
string attachments = "";
if (attachmentFiles.Length > 0)
{
 foreach (string file in attachmentFiles.Split(';'))
 {
  string virtualFile = virtualFolder + file;
  EPiServer.Web.Hosting.UnifiedFile uf = System.Web.Hosting.HostingEnvironment.VirtualPathProvider.GetFile(virtualFile) as EPiServer.Web.Hosting.UnifiedFile;
  attachments += uf.LocalPath + "," + file + ";";
 }
 if (attachments.Contains(";"))
 {
  attachments = attachments.Substring(0, attachments.Length - 1);
 }
}
// -------- END Finished Building attachment string
// Pass the attachments string to send mail function

//In the send mail function
if (attachments.Length != 0)
{
 foreach (string attach in attachments.Split(';'))
 {
  string[] file = attach.Split(',');
  Attachment attachment = new Attachment(file[0]);
  attachment.Name = file[1];
  msg.Attachments.Add(attachment);
 }
}