Author: Gedalya Date: To: exim-users CC: Turritopsis Dohrnii Teo En Ming Subject: Re: [exim] Please help me to understand the roles and purposes of
an Exim Smarthost
On 8/26/21 9:47 PM, Turritopsis Dohrnii Teo En Ming via Exim-users wrote: > My boss said that the Exchange server in the same private internal
> network was rejecting emails from the Linux server because the emails
> were marked as spam. He told me I would need to configure Exim SMTP
> server to relay emails to the Exchange server in the same private
> internal network.
> The recipient domain is hosted in the Exchange server. Please read
> below for the Exim Smarthost which my boss had configured. I still do
> not fully understand the roles and purposes of a smarthost. Please
> help me to understand it. Thank you very much.
Based on what you're describing, the situation might be as follows (educated guessing included):
Without the manual route of teo-en-ming-corp.com via 192.168.252.2, the routing would fall through to DNS lookup and the mail will be delivered via the internet to mail.teo-en-ming-corp.com.
Your spam filter sees the mail coming from some hosting company's IP address, which always has a bad reputation. You can try to relay the mail via gmail, outlook.com or such (same idea: smarthost configuration, manual route) and then it would get treated better. But your boss says hey, we can just deliver it on the local network, much simpler! Assuming RFC1918 addresses (local, 192.168.x.x) are trusted.
"smarthost" typically means an "outgoing smtp server" like what you would configure in a mail client on your computer or smartphone, but in this case you are using it only for one destination domain via the route_data lookup.
As long as you have this router above your dnslookup router, and the lookup finds the domain in /etc/staticroutes, mail will be delivered to 192.168.252.2.
