Well, I cracked the code as to why my email alerts weren't working. Apparently, Verizon has suddenly changed their SMTP rules and I can't use port 25 outgoing to non-Verizon hosts anymore. That broke both of the D-Link boxes. I can fix the DNS-323 by using a different port, but the DNS-321 doesn't have the capability to use a different email server port, so that one remains broken.