How to send mail in Exim4 through different IPs?

Question

SMTP

There is a web-server with several IP. Each site has its own dedicated domain/IP.
Letters are sent from sites and need to be configured so that Exim correctly detects them and sends them from the correct IP.
Otherwise, Exim sends all mail from the IP of the main interface.
I believe that you need to make a regular match, because the configuration below can only specify 1 IP

remote_smtp:
driver = smtp
interface = <IP address>

We also need help - to compose the correct regular expression for helo_data.
Thanks in advance.

Answer 1

stolen from exim configs in cPanel

interface = ${if exists {/etc/mailips}{${lookup{$original_domain}lsearch{/etc/mailips}{$value}{${lookup{$sender_address_domain}lsearch{/etc/mailips}{$value}{${lookup{${perl{get_sender_from_uid}}}lsearch*{/etc/mailips}{$value}{}}}}}}}}
  helo_data = ${if exists {/etc/mailhelo}{${lookup{$original_domain}lsearch{/etc/mailhelo}{$value}{${lookup{$sender_address_domain}lsearch{/etc/mailhelo}{$value}{${lookup{${perl{get_sender_from_uid}}}lsearch*{/etc/mailhelo}{$value}{$primary_hostname}}}}}}}{$primary_hostname}}

file format:
/etc/mailhelo

10.10.10.10: domain1.com
10.10.10.11: domain2.com
*: domain3.com

/etc/mailips

domain1.com: 10.10.10.10
domain2.com: 10.10.10.11
*: 10.10.10.13