On 2018-05-12 (15:55 MDT), Thomas Smith <da-postfixusers...@abelonline.de> wrote: > > The documentation[1] and several e-mails here mention that > reject_unknown_client_hostname can reject legitimate e-mails. > > What exactly are these scenarios?
A mail sender doesn't have an A record. > When do they occur in real life? Yes. Not a lot, but they do and they tend to be important things that often have incompetent mail admin (banks, for example). > Are there really legitimate mail servers that don't have a reverse DNS record > that resolves to their IP? Yes. > I would like to know so that I can decide whether I should care and whether I > can use this option for my setup. If you receive mail for anyone else but yourself, you cannot. warn_if_reject reject_unknown_client_hostname will log times this would have happened. Try it for a few days and see what is logged. Last time I did it, it was a lot of mail that was wanted. Perhaps things are better in 2018, but I doubt it. -- "I've had a perfectly wonderful evening. But this wasn't it." - Groucho Marx
