Exim and several external addresses, which one will he choose?

Question

linux

Hello!

I have 2 servers, they run exim in docker as a mail sender from the site. Each server has its own external IP. I registered all this business in dns. But there is one more thing, there is another vrrp external that can migrate when one server crashes to another, it glows like a second ip on the interface. And it is highly undesirable for me that the sending would somehow take place through it. Either it must be correctly specified in the settings so that letters do not go to spam ... I

just can’t dig up the information at all whether he can start sending from it, so everything is going from the first ip for now ...

In theory, this second ip is registered in spf, and its PTR and A are the same. The only thing is that when sending a letter, the hostname will always be the same and it differs from zone A of the second IP address, there is a different name. Ie it turns out I send a letter with the hostname srv1.mymail.ru. But the address resolves PTR as srv2.mymail.ru but this address leads to the real IP from which the letter was sent and it is registered in spf. Fuf))
So far, porridge in my head with these validity checks :).

Answer 1

In my opinion it should be enough to bind Exim to the first ip, instead of 0.0.0.0.
But I would also run Exim as a separate user, which has its own routing table (network namespace), in which only default with a gateway for the first ip and default with a blackhole with a lower priority are among the routes.
By the way, I would like to see the output ip a sand ip r s table all
UPD. Here, it seems, what you need https://unix.stackexchange.com/questions/342607/on... is not what I said, but more correctly.