I gave up trying to get email authentication to work, and did a clean 6.0b3 install by doing the following:
use "backup to desktop" to backup user stuff etc on broken system
clean install 6.0b3
restore from desktop... didn't work, browser kept timing out, so I scp'd the smeserver.tgz to the new server, and untarred it from the / directory, then did a post update and reboot.
This appears to have worked, though it did not restore anything in the /opt directory, nor any!!!! of the sql databases.
AFAIAK, this sux that the regular backup does not maintain myql database info., nor stuff in /opt which is where my custom installs are..
Sigh.
Time to look at Shad's arkeia stuff