I posted earlier and got no response and just wanted to follow up once more.
I have RL-ARM TCPnet setup on a device and it only connects and sends and email via the SMTP functions about 50% of the time; all other times it comes back with SMTP_EVT_TIMEOUT or SMTP_EVT_ERROR as shown here: http://www.keil.com/support/man/docs/rlarm/rlarm_smtp_connect.htm
Unfortunately the descriptions of what those error mean is very lacking: in terms of what caused any possible timeout or protocol error.
The following page has a link for error functions but the link actually just takes you to the Ethernet functions page. http://www.keil.com/support/man/docs/rlarm/rlarm_tn_func_ref.htm
I have run Wireshark but the switch I'm using doesn't support port mirroring so I have no way to see the actual data entering and leaving the device and onto the network. I can however see the DHCP request, offer, ack etc.
If anyone has used the TCPnet libraries before and has had any experience with the SMTP functionality, any help is appreciated.