Set Exim smtp_active_hostname based on IP being connected to
As a system administrator, I would like smtp_active_hostname variable to be set based on the IP that is being connected to when there are accounts that are set to use a dedicated IP, so that other settings and functionality of exim that use the variable can use the correct server name rather than the mis-matched underlying primary server name.
The smtp_active_hostname is used in a number of places to set the correct server name in headers etc. In order to support smarthosts where a dedicated IP is intended to be used for a specific account / domain, the smtp_active_hostname should be set based on the IP address that the client is connecting to.
The current workaround is to use the /etc/mail_reverse_dns file (like below). It would be nice if this was either set this way by default or if the smtp_active_hostname defaulted correctly when the setting isn't explicitly set.