Hi Cactus,
Hmm, stranger and stranger...
My MESSAGES log file is very long so I don't want to clog up this BB with the listing. I had a look at it from the last reboot, (this afternoon), but could find no obvious problems. 
I have listed here my "Review Configuration" listing for you to have a look at. 
One thing of note is that when I built the server the server name was abc-gateway and later I changed it via the server-manager panel (Configuration > Workgroup), to abc-mail for conformity with the old SME 6 server. This is maybe where things went wrong. What do you think?
Review configuration
Networking Parameters 
Server Mode servergateway 
Local IP address / subnet mask 192.168.1.122/255.255.255.0 
External IP address / subnet mask 10.10.10.2/255.255.255.0 
Gateway 10.10.10.1 
Additional local networks 192.168.1.0/255.255.255.0 
DHCP server enabled 
Beginning of DHCP address range 192.168.1.65 
End of DHCP address range 192.168.1.85 
Server names 
DNS server 192.168.1.122 
Web server www.abc-suisse.ch 
Proxy server proxy.abc-suisse.ch:3128 
FTP server ftp.abc-suisse.ch 
SMTP, POP, and IMAP mail servers mail.abc-suisse.ch 
Domain information 
Primary domain abc-suisse.ch 
Virtual domains abc-suisse.ch 
Primary web site http://www.abc-suisse.ch 
Server manager https://abc-gateway/server-manager/ 
User password panel https://abc-gateway/user-password/ 
Email Addresses useraccount@abc-suisse.ch
firstname.lastname@abc-suisse.ch
firstname_lastname@abc-suisse.ch