In this post suggested using the Satellite system option. However, this seems to do the same as the mail sent by smarthost; no local mail option in exim – i.e. even local mail to root tries to go via the smarthost, which then complains. The Internet with smarthost option is probably the better choice (equivalent to exim’s mail sent by smarthost; received via SMTP or fetchmail).
N.B. Normal proxmox setup seems to be for postfix to use /etc/aliases directly. Double check this file!
