I'm trying to bring a new server online for a customer, and they're apparently not going to allow a reverse DNS lookup, which will make it difficult or impossible to send mail from the server. I can send it through a smarthost, one of my other servers, but exim4 also does a reverse DNS check during the helo negotiation. through some trial-and-error, though, I got it to bypass for this host, in /etc/exim4/update-exim4.conf.conf:
MAIN_HOST_LOOKUP=!198.6.16.76
just like that, no quotes. if I ever have to make it a list, it'll probably take more experimentation. remember to run update-exim4.conf afterwards, and restart the service.
last updated 2018-11-16 16:33:04. served from tektonic.jcomeau.com