A tip: generate some information in the error log so you can tell what's going on. For instance, you might add a message to the error log using warn with something like:

foreach my $line(@lines){
    warn "Trying to attach file [$line]";
    $msg->attach(Type     =>'image/gif',
                 Path     =>"/u619/be/bon/uploads/$line",
                 Filename =>"$line",
                 Disposition => 'attachment'
                 );
}
$msg->send;
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If you did this, you might find that your filename has a newline in it, which may prevent MIME::Lite from locating it properly. Try adding the following line after you close the file:

chomp @lines;
[download]

The following example of MIME::Lite usage may also be helpful: RE: sending email

Chris
M-x auto-bs-mode