the first person i spoke to at Apple support wasn't very helpful. i tried another support person later, and recommended toggling Setting-->Airplane Mode on and off for 10 seconds straight.
after doing that, i was able to send an email thru EDGE.
i'm not sure if this helps long-term, but at least i was able to get the email sent. if any others have similar problems, give this a try.
i deleted my dotmac account first, went airplane mode and then redid the account...using the att emailserver CWMX.com for smtp outgoing
WORKED!
eta: this worked on cox using wifi to boot, no idea about edge
eta again: ok, well, now i can send messages on the iPhone, but can't on my mac!!!
eta 3rd time...
ok, turned my mac back to smtp.mac.com
synced again...
everything is fine, can send mail from both and receive on both WITHOUT using CWMX.com as my smtp server
i dunno what to say but play with the thing