Postfix-based Mail Transport Agent

Variables

Accepting mail

mta_is_destination (bool): if true, the mydestination postfix parameter will be set to $myhostname. This is required to accept mail for local delivery.
mta_alias_maps (list of things): map local aliases to user names or pipes or remote mail addresses.

If mta_alias_maps is false or empty, or mta_is_destination is false, local delivery will be shunted to a 5.1.1 error.

Each thing in the list can have the following attributes:
- thing.file (required, string): Path to the file where the alias map is stored. Usually, one of the things should be managing /etc/aliases.
- thing.map (mapping of addresess to targets): This works like the map in mta_virtual_maps.
- thing.owner (optional, user name): The UNIX user which will own the file. This has semantics with Postfix, namely piped commands will be executed under the user and group to which the file belongs, if its not UID 0.
- thing.group (optional, group name): The UNIX group to which the file will belong. See above for details.
- thing.mode (optional, chmod-compatible mode specfication): The mode to use for the aliases file.
Note that using a restrictive mode (e.g. no write permissions for the owning user) may not properly work, as the postalias command must be able to write in the same directory and will do so as the user to which the file belongs.
mta_listen (bool, default true): if true, postfix will be configured to listen on port 25 for incoming connections.
mta_domains (list of strings): the list of domains for which the MTA shall accept mail. This is independent from mta_is_destination -- domains may be purely for forwarding purposes.
mta_message_size_limit (integer, default 10240000): Maximum size of emails that postfix will accept in bytes (on either service, smtpd or submission).
mta_postscreen (thing or false): If not false, the postscreen service will be enabled.

In that case:
- mta_postscreen.greet (thing or false): If not false, the multipart greeting will be used by postscreen.
  
  In that case:
  - mta_postscreen.greet.action (string): The action to take when a client fails the greet test, see postscreen_greet_action in the postconf manual.
  - mta_postscreen.greet.banner (string, optional): A custom string for the first part of the greet banner. Must contain the hostname as first substring, see also postscreen_greet_banner in the postconf manual.
- mta_postscreen_dnsbl (thing or false): If not false, dnsbl checks will be enabled. Make sure to have a local caching resolver.
  
  In that case:
  - mta_postscreen.dnsbl.sites (list of strings): Postfix DNSBL strings, which consist of a hostname and an optional weighting. See postscreen_dnsbl_sites in the postconf manual for details. Note that this needs to be a YAML list, not a string with comma separated items.
  - mta_postscreen.dnsbl.action (string): The action to take when a client fails the DNSBL check. See postscreen_dnsbl_action.
  - mta_postscreen.dnsbl.threshold (integer): The threshold for a client to fail the test.
mta_virtual_maps (list of things). The things can either be strings, in which case they are taken verbatimly in the virtual_alias_maps parameter of postfix. Otherwise, they must be hashes with the following characteristics:
- thing.domain (string): The domain for which this mapping shall be used
- thing.map (mapping from localparts to strings): The mapping from the localpart to the delivery destination. The values may also be lists of strings, which will be joined with ,.
Example:
```
mta_virtual_maps:
  - domain: foo.example
    map:
      postmaster:
       - fred
       - juliet
      webmaster: root
      sales: sales@bar.example
```
mta_relayhost (string): If set, postfix will relay non-local mail through this destination. Refer to the postfix documentation on the relayhost directive for details.

This setting is useful to achieve a “satellite system” type of setup in which all mail is relayed through another server instead of being delivered directly; it will typically be used for MTAs that only need to send cron mails etc.
mta_relayhost_auth_username (string): This is only meaningful if mta_relayhost is set. In that case this set the SASL user name to use to set up authentication with the relay host using SASL.
mta_relayhost_auth_password (string): The password to use for relayhost SASL authentication. Required if mta_relayhost_auth_username is used.
mta_relayhost_auth_mapfile (path): A path where a config file containing the SASL authentication credentials will be written to.
mta_transport_map (mapping): A lookup table, mapping destination address patterns to their respective nexthop. Refer to the postfix transport(5) manual for details on the format of this table.

Example:
```
mta_transport_map:
  "example.com": "smtp:server-1.example.com"
  "example.org": "smtp:server-1.example.org"
```
mta_smtpd_client_restrictions (list of strings, default empty): Add client restrictions for the server to apply. See smtpd_client_restrictions.
mta_smtpd_helo_required (bool, default false): smtpd_helo_required
mta_strict_rfc821_envelopes (bool, default false): strict_rfc821_envelopes
mta_smtpd_helo_restrictions (list of strings, default empty): Add HELO restrictions for the server to apply. See smtpd_helo_restrictions.
mta_smtpd_sender_restrictions (list of strings, default empty): Add sender restrictions for the server to apply. See smtpd_sender_restrictions.
mta_smtpd_relay_restrictions (list of strings, default ["reject_unauth_destination"]): Add relay restrictions for the server to apply. See smtpd_relay_restrictions.

Note: When overriding the default value, make sure to include at least reject_unauth_destination in your list of restrictions to prevent your MTA from becoming an open relay!
mta_smtpd_recipient_restrictions (list of strings, default empty): Add recipient restrictions for the server to apply. See smtpd_recipient_restrictions.

Mail submission agent

If mta_msa is not false, the submission port is opened and the following settings apply (only for the submission smtpd, not for the regular, port 25, smtpd):

mta_msa_sasl_type (string): Value for the postfix smtpd_sasl_type setting.
mta_msa_sasl_path (string): Value for the postfix smtpd_sasl_path setting.

Both of the above sasl settings need to be set to enable SASL authentication. Note that the relay restrictions are configured so that SASL authentication is required on the submission port to allow sending mail.

mta_msa_dkim (bool): Enable the OpenDKIM milter for mail submitted via the MSA. Requires mta_dkim to be configured properly.

TLS

mta_tls_cert_file (string): Path to the TLS certificate
mta_tls_key_file (string): Path to the TLS private key
mta_tls_security_level (string, default "may"): Value of postfix’s smtpd_tls_security_level directive.
mta_tls_log (bool, default false): Enable logging of TLS connections, e.g. for cipher statistics

OpenDKIM

If mta_dkim is not false, the settings below become available and OpenDKIM will be configured.

mta_dkim_sign (bool): Whether the OpenDKIM milter shall sign mail for the domains listed in mta_dkim_domains.
mta_dkim_verify (bool): Whether the OpenDKIM milter shall verify mail.
mta_dkim_domains (list of hashes): Configuration of keys and domains for automatic DKIM signing. Each entry must have the following keys:
- name (string): The domain name to sign for
- key (string): Name part of the key.
This produces key entries like:

{{ key }}._domainkey.{{ name }} and keys must be in /etc/opendkim/keys/{{ name }}/{{ key }}.private.

Safety nets and misc

mta_soft_bounce (bool, default false): if true, soft_bounce is enabled. In that case, postfix will return temporary error codes instead of permanent if local delivery fails due to unknown users.
mta_delay_warning (string, optional): If set, this is the value of the delay_warning_time setting of postfix.
mta_override_hostname (string, optional): If set, this is used as value for myhostname instead of the value of inventory_hostname.

If you’d like to add further files from another role, install them to /etc/postfix/aliases.d/ using file names ending in .aliases, and notify the update include alias file handler. These files will automatically be concatenated and installed to /etc/postfix/aliases.

Running additional services

mta_services (list of dictionaries). Each dictionary describes a service

that should be added to the master.cf.

Example:

mta_services:
  - port: 5870
    type: inet
    command: smtpd
    options:
      smtpd_tls_security_level: encrypt
      smtpd_relay_restrictions:
        - permit_sasl_authenticated
        - defer_unauth_destination

Mailman

mta_use_mailman (bool, default false): Set this to enable the mailman transport.
mta_mailman_script_location (string, default /usr/lib/mailman/bin/postfix-to-mailman.py): Location of the postfix-to-mailman.py program.

agdsn/ansible-mta