[Postfix](http://www.postfix.org/) with ldap authentication and [spamassassin](http://spamassassin.apache.org/) + [OpenDKIM](http://www.opendkim.org/) in ldap.

# Volumes
- `/etc/ssl/mail:ro`: certificates have to be here.

# Environment Variables
## MYHOSTNAME
Fully qualified hostname.

## MYDOMAIN
The internet domain name of the mail system.

## SMTP_BANNER
Text prepended to `$myhostname ESMTP $mail_name` for the smtp banner.

## SPAMASSASSIN_HOST
Hostname for the spamassassin host.

## DOVECOT_HOST
Hostname for the dovecot host.

## DOVECOT_AUTH_PORT
Port for the dovecot host.

## DKIM_HOST
Hostname for the OpenDkim host.

## DKIM_PORT
Port for the OpenDkim host.

## LMTP_HOST
Hostname for the lmtp host (probably dovecot).

## LMTP_PORT
Port for the lmtp host.

## LDAP_URI
Complete uri for the authentication ldap host.

## LDAP_BIND_DN
DN used to authenticate against ldap.

## LDAP_BIND_PASSWORD
Password used to authenticate against ldap.

## LDAP_ALIAS_QUERY_FILTER
Ldap filter for mail aliases.

## LDAP_DOMAIN_QUERY_FILTER
Ldap filter for domains.

## LDAP_MAILBOX_QUERY_FILTER
Ldap filter for mailboxes.

## LDAP_MAILBOX_SEARCH_BASE
Base DN to look for mailboxes on the ldap host.

## LDAP_DOMAIN_SEARCH_BASE
Base DN to look for valid domains on the ldap host.

## LDAP_DOMAIN_RESULT_ATTRIBUTE
- default: dc

Ldap attribute that is fetched in the domain query.

## LDAP_MAILBOX_RESULT_ATTRIBUTE
- default: cn

Ldap attribute that is fetched in the mailbox query.

## LDAP_STARTTLS
- default: yes

Whether to use tls when connecting to the ldap host.

## CERT_NAME
- default: fullchain.pem

Name of the certificate file.

## KEY_NAME
- default: privkey.pem

Name of the key file.

## MESSAGE_SIZELIMIT
- default: 20000000

Message size limit in bytes.

## MAILBOX_SIZELIMIT
- default: 0

Mailbox size limit in bytes. `0` disables the limit.

## TLS_SECURITY_LEVEL
- default: may

One of:
- none: TLS will not be used. 
- may: Opportunistic TLS: announce STARTTLS support to remote SMTP clients, but do not require that clients use TLS encryption. 
- encrypt: Mandatory TLS encryption: announce STARTTLS support to remote SMTP clients, and require that clients use TLS encryption. 
  According to [RFC 2487](http://tools.ietf.org/html/rfc2487) this MUST NOT be applied in case of a publicly-referenced SMTP server.

## TLS_PROTOCOLS
- default: !SSLv2, !SSLv3

Comma seperated list of accepted TLS protocols.

## TLS_CIPHERS
- default: high

The minimum TLS cipher grade that the Postfix SMTP server will use with opportunistic TLS encryption.

## TLS_EXCLUDE_CIPHERS
- default: aNULL, MD5, 3DES

Comma seperated list of ciphers or cipher types to exclude from the SMTP server cipher list at all TLS security levels.

# Ports
- 25
- 587

# Capabilities
- DAC_OVERRIDE
- NET_BIND_SERVICE
- SETGID
- SETUID