How to check encrypted emails ?

[MMS]

To save all attachments from my e-mails to file on the disk I wrote a
program available in the examples on the msdn pages:

if(item.Attachments.Count>0)
{
for (int i; i<=item.Attachments.Count;i++)
{
item.Attachments[i].SaveAsFile(@"C:\FileSave\" +
item.Attachments[i].FileName);
Console.WriteLine(item.Attachments[i].DisplayName.ToString());
}
}

But if messages is encrypted I receive an exception "Your Digital ID
name cannot be found security system." Maybe anyone knows how to check
before that the content is encrypted ?