[Dovecot](http://www.dovecot.org/) with imap, starttls, ldap authentication, sieve rules in ldap.

Uses [SSMTP](https://packages.debian.org/stable/mail/ssmtp) to send mails (for example if you have a redirect sieve rule).

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

# Environment Variables
## HOSTNAME
Fully qualified name of the mail host.

## SSMTP_MAIL_RELAY
Hostname and port for the used smtp relay (for example `mail.example.com:587`).

## SSMTP_USER
User to authenticate agains the smtp relay.

## SSMTP_PASSWORD
Password to authenticate agains the smtp relay.

## SSMTP_AUTH_METHOD
- default: LOGIN

Which authentication mechanism to use for the smtp relay.

## SSMTP_USE_STARTTLS
- default: yes

Whether to use starttls for the smtp relay.

## LDAP_HOST
Ldap hostname (can include the port).

## LDAP_SIEVE_HOST
Has to be the same as `LDAP_URI` but in a different format (like `ldap:389`).

## LDAP_BIND_DN
DN used to authenticate against ldap.

## LDAP_BIND_PASSWORD
Password used to authenticate against ldap.

## LDAP_BASE_DN
Base DN to look for users on the ldap host.

## LDAP_SCOPE
- default: subtree

Search scope of ldap queries.

## LDAP_PASS_FILTER
Specifies the filter on how user is found on the ldap host.
[Dovecot variables](http://wiki2.dovecot.org/Variables) can be used.

## LDAP_USER_ATTRIBUTE
- default: cn

The ldap attribute which stands for the username.

## LDAP_PASSWORD_ATTRIBUTE
- default: userPassword

The ldap attribute which stands for the password.

## LDAP_SIEVE_ATTRIBUTE
- default: sieve

The ldap attribute which contains the sieve rules.

## LDAP_USE_TLS
- default: yes

Whether to use tls when connecting to the ldap host.

## LDAP_APP_PASSWORDS_BASE_DN
Base DN to look for app passwords for a user.

## LDAP_APP_PASSWORDS_FILTER
Specifies the filter on what counts as an app password.

## ALLOWED_USERNAME_CHARS
- default: äöüabcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@

List of characters allowed in a username.

## AUTH_MECHANISMS
- default: plain

Space seperated list of supported [authentication mechanisms](http://wiki2.dovecot.org/Authentication/Mechanisms).

## CERT_DOMAIN
Name of the certificate domain.

## SSL_DH_LENGTH
- default: 2048

Length of the Diffie-Helman key in bits.

## SSL_MIN_PROTOCOL
- default: TLSv1.2

Ssl minimum protocol version.

## SSL_CIPHERLIST
- default: ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256

Colon seperated list of supported ciphers (`!`disables a cipher).

Go [here](https://www.openssl.org/docs/manmaster/man1/ciphers.html) for a list
of ciphers.

## IMAP_MAX_USER_CONNECTIONS
- default: 10

Maximum number of connections from the same user + ip.

# Ports
- 143

# Capabilities
- CHOWN
- DAC_OVERRIDE
- FOWNER
- NET_BIND_SERVICE
- SETGID
- SETUID
- SYS_CHROOT