!!! warning Changing the binding does not affect source NAT. See [SNAT](../post_installation/firststeps-snat.en.md) for required steps. ## IPv4 binding To adjust one or multiple IPv4 bindings, open `mailcow.conf` and edit one, multiple or all variables as per your needs: ``` # For technical reasons, http bindings are a bit different from other service bindings. # You will find the following variables, separated by a bind address and its port: # Example: HTTP_BIND=1.2.3.4 HTTP_PORT=80 HTTP_BIND= HTTPS_PORT=443 HTTPS_BIND= # Other services are bound by using the following format: # SMTP_PORT=1.2.3.4:25 will bind SMTP to the IP 1.2.3.4 on port 25 # Important! Specifying an IPv4 address will skip all IPv6 bindings since Docker 20.x. # doveadm, SQL as well as Solr are bound to local ports only, please do not change that, unless you know what you are doing. SMTP_PORT=25 SMTPS_PORT=465 SUBMISSION_PORT=587 IMAP_PORT=143 IMAPS_PORT=993 POP_PORT=110 POPS_PORT=995 SIEVE_PORT=4190 DOVEADM_PORT=127.0.0.1:19991 SQL_PORT=127.0.0.1:13306 SOLR_PORT=127.0.0.1:18983 ``` To apply your changes, run `docker compose down` followed by `docker compose up -d`. ## IPv6 binding Changing IPv6 bindings is different from IPv4. Again, this has a technical background. A `docker compose.override.yml` file will be used instead of editing the `docker compose.yml` file directly. This is to maintain updatability, as the `docker compose.yml` file gets updated regularly and your changes will most likely be overwritten. Edit to create a file `docker compose.override.yml` with the following content. Its content will be merged with the productive `docker compose.yml` file. An **example** IPv6 **2001:db8:dead:beef::123** is given. The first suffix `:PORT1` defines the external port, while the second suffix `:PORT2` routes to the corresponding port inside the container and must **not** be changed. ``` version: '2.1' services: dovecot-mailcow: ports: - '[2001:db8:dead:beef::123]:143:143' - '[2001:db8:dead:beef::123]:993:993' - '[2001:db8:dead:beef::123]:110:110' - '[2001:db8:dead:beef::123]:995:995' - '[2001:db8:dead:beef::123]:4190:4190' postfix-mailcow: ports: - '[2001:db8:dead:beef::123]:25:25' - '[2001:db8:dead:beef::123]:465:465' - '[2001:db8:dead:beef::123]:587:587' nginx-mailcow: ports: - '[2001:db8:dead:beef::123]:80:80' - '[2001:db8:dead:beef::123]:443:443' ``` To apply your changes, run `docker compose down` followed by `docker compose up -d`.