4. Mail Server Configuration

Abstract

 SMTP stands for “Simple Mail Transfer Protocol”. An SMTP server allows you to send internal and external mail through it. If your server is referenced on the Internet public DNS as an MX server for your domain name, then it also receives and manages mail from the Internet addressed to users of your domain. This wizard allows you to setup a mail server with Postfix.

[Warning] Warning

Your server network parameters must not be provided by DHCP for Postfix to work properly.

The first step consists of choosing whether you intend to use an external SMTP relay or not. If you can use one provided by your ISP then choose Relay mail server in the drop-down list. Otherwise, choose Main mail server. In the procedure below only the second step differs from one configuration to the other.

  1. Global Postfix Configuration

    Smtpd banner

    The banner your server advertises when talking to other servers or clients.

    Hostname

    The FQDN name of your server.

    Domain

    The domain handled by this mail server.

    Origin

    The domain name that locally-posted mail appears to come from, and that locally posted mail is delivered to.

  2. Relay (for Relay mail server only)

    Relay host

    This is where you define the mail server responsible for relaying your outgoing messages.

    Relay domains

    What destination domains (and subdomains thereof) this system relays mail to. Mails sent to a domain other than the local domain that are not part of the relay domains are rejected (to prevent spam).

  3. Main server Configuration (for Main mail server only)

    helo required

    For security reasons you might require remote clients to identify themselves before starting communication. Choose yes in this case.

    Disable verify command

    The verify command can be used by a client to verify a specific user is actually handled by a mail server. You can disable it to prevent email harvesting by spammers.

    Masquerade domains

    This field is used to masquerade the domain from which internal mail appears to come from. For example: foo.example.com example.com directs Postfix to masquerade toto@foo.example.com to toto@example.com.

  4. Message options

    A few options affecting message handling you can leave at their default values.

    Maximal queue life

    If a message cannot be delivered after this delay it is sent back as undeliverable. Expressed as a number of days prefixed by the letter d, for example 3d means three days.

    Message size limit

    Messages larger than this size (kilobytes) are rejected. When defining this parameter, please bear in mind that binary attachments have a bigger size than their filesize because they have to be encoded differently to be sent in a mail message.

    Delay warning time

    If a message cannot be delivered, the sender will receive a warning after this number of hours.

  5. Network Configuration

    inet interfaces

    The network interface addresses that this mail system receives mail on. By default the server listens on all network interfaces (all), specify localhost to listen only on the local interface.

    my destination

    The list of domains that are delivered via the local mail delivery transport. The SMTP server validates recipient addresses and rejects non-existent recipients.

    my networks

    The list of “trustedSMTP clients who have more privileges than “strangers”. In particular, “trustedSMTP clients are allowed to relay mail through Postfix. Specify a list of network addresses or network/netmask patterns, separated by commas and/or whitespace.

If a parameter is not clear to you, please refer to the Postfix Configuration Parameters.