E-Mail
On each server, a local Postfix instance is running to deliver mails to their destination.
SPF Record
To explicitly allow your server to send mails from a particular domain, you need to add an SPF record to your DNS zone:
example.com. 3600 IN TXT "v=spf1 mx a:<fqdn-or-smarthost> -all"
Note
depending on your companys guideline, servers can send mails directly or through a designated smarthost
Warning
please make sure to include all other servers that should be able to send mails from your domain as well
Configuration
Warning
changing any values can led to unintended consequences. Please make sure to plan any changes carefully and ask us for advice if you’re in doubt
mynetworks
list of trusted remote SMTP clients that have more privileges than strangers
see the Postfix documentation for details
default:
127.0.0.0/8 [::1]/128
relayhost
next-hop destination of non-local mail
see the Postfix documentation for details
default: empty
envelope_from
rewrite envelope from of each sent mail to the address specified
useful to catch any return errors at a particular mailbox without configuring all applications independently
default: empty (internally defaults to <username@server-domain>)
smtp_fallback_relay
optional list of relay hosts for SMTP destinations that can’t be found or that are unreachable
see the Postfix documentation for details
default: empty
inet_interfaces
network interface addresses that this mail system receives mail on
see the Postfix documentation for details
default:
loopback-only
(localhost Port 25)
message_size_limit
the maximal size in bytes of a message, including envelope information
see the Postfix documentation for details
default:
25600000
(25MB)
monitoring
whether our external monitoring will check the condition of the mail service on this particular server
default: true
smtpd_tls_cert_file
path to a TLS certificate used for incoming SMTP connections
default: empty
smtpd_tls_key_file
path to a TLS key used for incoming SMTP connections
default: empty
smtputf8_enable
Enable preliminary SMTPUTF8 support for the protocols described in RFC 6531 to 6533
see the Postfix documentation for details
default:
yes
Example
{
"postfix::relayhost": "example.net",
"postfix::envelope_from": "webserver@example.net"
}