Outbound Server setup

Bizquick2k

New Member
Sep 30, 2025
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I'm having a little bit of trouble setting this up.
I need to setup this server to be a outbound relay to mimecast.

I have the server's IP mapped to a IP translated to an allowed IP for mimecast. and I configured that in the Relay Hosts.

But I cant figure out what I'm missing. I'm trying to do test emails to see if it will send the email out to mimecast and then back to me. But it looks like its just trying to send it to its self. Do I have to empty out the allowed domains?
 
If have postfix as mail server, that is very easy to setup:

1. On Proxmox Mail Gateway:
  • Configuration -> Mail Proxy -> Relay Domains and click on Create. Add Your domain.
1759307377380.png
  • Configuration -> Mail Proxy -> Transports and click on Create. Add Your domain, IP(address of Your mail server), protocol SMTP,port 25
1759307462711.png

2. On Mail Server (example if using postfix):
  • create file /etc/postfix/transport and add Your domain and replace IP with address of Your ProxMox Mail Gateway
example.com :
.example.com :
* smtp:[192.168.1.11]:26
  • generate db file
Code:
postmap hash:/etc/postfix/transport
  • Add in /etc/postfix/main.cf
Code:
transport_maps = hash:/etc/postfix/transport
  • restart postfix service
Code:
systemctl restart postfix