More and more mail servers are starting to reject email if your outgoing mail server doesn’t have a reverse DNS record or PTR record. You can check if you have one by issuing the following command: dig -x 127.0.0.1 Obviously, replace the 127.0.0.1 address with the relevant IP address of your mail server. You should [...]
We use Postfix as a dropin replacement for Sendmail on our servers. We wanted to configure postfix to relay email via our internal mail server for internal email addresses, and send directly if the email address was external. To do this, follow these steps: Edit the /etc/postfix/transport file and add the following line: myinternaldomain.com smtp:[ipaddress]:25 [...]
We have been having problems sending emails from our mail server (running Kerio) to a particular domain over the past few weeks. We kept receiving bounce emails with the following: 550 Rule imposed. Sender using invalid hostname in greeting as per RFC specification. After trying all manner of solutions, it turned out to be a problem with [...]