Warning: This document is for the development version of Mailu. The main version is 1.5.

Mailu configuration settings

Common configuration

The SECRET_KEY must be changed for every setup and set to a 16 bytes randomly generated value. It is intended to secure authentication cookies among other critical uses.

The DOMAIN holds the main e-mail domain for the server. This email domain is used for bounce emails, for generating the postmaster email and other technical addresses.

The HOSTNAMES are all public hostnames for the mail server. Mailu supports a mail server with multiple hostnames. The first declared hostname is the main hostname and will be exposed over SMTP, IMAP, etc.

The POSTMASTER is the local part of the postmaster email address. It is recommended to setup a generic value and later configure a mail alias for that address.

The AUTH_RATELIMIT holds a security setting for fighting attackers that try to guess user passwords. The value is the limit of requests that a single IP address can perform against IMAP, POP and SMTP authentication endpoints.

Mail settings

The MESSAGE_SIZE_LIMIT is the maximum size of a single email. It should not be too low to avoid dropping legitimate emails and should not be too high to avoid filling the disks with large junk emails.

The RELAYNETS are network addresses for which mail is relayed for free with no authentication required. This should be used with great care. It is recommended to include your Docker internal network addresses if other Docker containers use Mailu as their mail relay.

The RELAYHOST is an optional address of a mail server relaying all outgoing mail.

The FETCHMAIL_DELAY is a delay (in seconds) for the fetchmail service to go and fetch new email if available. Do not use too short delays if you do not want to be blacklisted by external services, but not too long delays if you want to receive your email in time.

The RECIPIENT_DELIMITED is a character used to delimit localpart from a custom address part. For instance, if set to +, users can use addresses like localpart+custom@domain.tld to deliver mail to localpart@domain.tld. This is useful to provide external parties with different email addresses and later classify incoming mail based on the custom part.

The DMARC_RUA and DMARC_RUF are DMARC protocol specific values. They hold the localpart for DMARC rua and ruf email addresses.

Web settings

The WEB_ADMIN contains the path to the main admin interface, while WEB_WEBMAIL contains the path to the Web email client.

Both SITENAME and WEBSITE are customization options for the panel menu in the admin interface, while SITENAME is a customization option for every Web interface.

Advanced settings

The PASSWORD_SCHEME is the password encryption scheme. You should use the default value, unless you are importing password from a separate system and want to keep using the old password encryption scheme.

Infrastructure settings

Various environment variables HOST_* can be used to run Mailu containers separately from a supported orchestrator. It is used by the various components to find the location of the other containers it depends on. They can contain an optional port number. Those variables are:

  • HOST_IMAP: the container that is running the IMAP server (default: imap, port 143)
  • HOST_LMTP: the container that is running the LMTP server (default: imap:2525)
  • HOST_HOSTIMAP: the container that is running the IMAP server for the webmail (default: imap, port 10143)
  • HOST_POP3: the container that is running the POP3 server (default: imap, port 110)
  • HOST_SMTP: the container that is running the SMTP server (default: smtp, port 25)
  • HOST_AUTHSMTP: the container that is running the authenticated SMTP server for the webnmail (default: smtp, port 10025)
  • HOST_ADMIN: the container that is running the admin interface (default: admin)
  • HOST_ANTISPAM: the container that is running the antispam service (default: antispam:11334)
  • HOST_WEBMAIL: the container that is running the webmail (default: webmail)
  • HOST_WEBDAV: the container that is running the webdav server (default: webdav:5232)
  • HOST_REDIS: the container that is running the redis daemon (default: redis)

Additional variables are used to locate other containers without dialing a specific port number. It is used to either whitelist connection from these addresses or connect to containers on the docker network:

  • FRONT_ADDRESS: the nginx container address (default: front)
  • WEBMAIL_ADDRESS: the webmail container address (default: webmail)
  • IMAP_ADDRESS: the webmail container address (default: webmail)