I have found similar posts to my problem but so far no answers...according to BOL
"Database Mail uses the Microsoft Windows security context of the current user to
control access to files. Therefore, users who are authenticated with SQL Server
Authentication cannot attach files using @file_attachments. Windows does
not allow SQL Server to provide credentials from a remote computer to another
remote computer. Therefore, Database Mail may not be able to attach files from a
network share in cases where the command is run from a computer other than the
computer that SQL Server runs on."
So my problem is I am running the command from the computer that SQL Server is running on but when I try to include a file attachment from a network share I am getting the MSG 22051 Attachment file XXX is invalid. Has anyone successfully sent an attachment from a network share using sp_send_dbmail or is Books Online just plain wrong?