It turns out that both the ISY and the ELK M1 (with the ethernet expander) couldn't send mail on my network. It all worked until I got FIOS installed. After investigation, it turns out that both the ACTIONTEC and WESTELL routers are blocking the SMTP communciation over the router. If you look in the firewall log it has something to do with the header. It doesn't matter what SMTP server you use (gmail, verizon, anything) the router is doing the block. Port forwarding, triggering, etc don't solve the problem.
My PCs can all send SMTP just find with any account. I used a command line sendmail tool to test and had no problems.
So, I set up a SMTP relay on the PC and pointed both the ISY and the ELK M1 at my new local SMTP server. That server then relays and sends through GMail. It works perfectly.
I think this has something to do with network stack that both ISY and ELK use.
I believe this is a problem for everyone who uses FIOS with one of these modems.