I'm trying to set up postfix as a null client, that is, I just want local linux users to be able to send mails outside using postfix's sendmail binary.
No reception of emails, no relaying for other hosts, no local mail delivery to users (I don't see any use for it).
I just want to allow sending emails outside.
I have set these parameters in /etc/postfix/main.cf:
myhostname = mail.thisisadomain.com
inet_interfaces = loopack-only
mydestination =
Should I set other parameters or change anything else in the configuration ?
I'm particularly interested in knowing what to do with the relayhost
parameter, since I don't understand what it does.
I've read the doc here http://www.postfix.org/STANDARD_CONFIGURATION_README.html#null_client but I still don't understand what the relayhost
parameter does, and if it matters for a null client.
Thanks for your help.
Best Answer
As far as I understood, the author of http://www.postfix.org/STANDARD_CONFIGURATION_README.html#null_client assumed that null client is not an always-online-server e.g. sometimes it can safely be turn off or isolated from internet. This snippet from that page
Without
relayhost
parameter, whenever the null client turned off, the email on your deferred queue will not retried until the server goes back online or turn on. So it possible when your machine turn on, the email queue already expired.The reason why you should provide
relayhost
parameter is no matter the state of your box (online or offline), therelayhost
server (the one who always stays online) will retry the stuck emails from your null client.