25 | smtp | Postfix | Normal smtp service, used for server-to-server communication. __WARNING__: This port __MUST__ be open, otherwise you cannot receive email sent from other servers. | YES
110 | pop3 | Dovecot | Used by end users to retrieve emails via POP3 protocol, secure connection over STARTTLS is available by default. | YES (open to your end users)
995 | pop3s | Dovecot | Used by end users to retrieve emails via POP3 protocol over SSL. Port 110 with STARTTLS is recommended. | YES (open to your end users)
143 | imap |Dovecot | Used by end users to retrieve emails via IMAP protocol, secure connection over STARTTLS is available by default. | YES (open to your end users)
993 | imaps | Dovecot | Used by end users to retrieve emails via IMAP protocol over SSL. Port 143 with STARTTLS is recommended. | YES (open to your end users)
4190 | managesieve | Dovecot | Sieve service used by end users to manage mail filters. Note: in old iRedMail releases, it's port 2000 (deprecated and not even listed in `/etc/services` file). | NO (disabled by default and users are forced to manage mail filters with webmail)
80 | http | Apache/Nginx | Web service | YES (open to your webmail users)
443 | https | Apache/Nginx | Web service over over SSL, secure connection. SOGo groupware provides Exchange ActiveSync (EAS) support through port 443. | YES (open to your webmail users)
3306 | mysql | MySQL/MariaDB | MySQL/MariaDB database service | NO (listen on `127.0.0.1` by default)
5432 | postgresql | PostgreSQL | PostgreSQL database service | NO (listen on `127.0.0.1` by default)
389 | ldap | OpenLDAP (or OpenBSD ldapd) | LDAP service, STARTTLS is available for secure connection. | NO (listen on `127.0.0.1` by default)
636 |ldaps | OpenLDAP (or OpenBSD ldapd) | LDAP service over SSL. Deprecated, port 389 with STARTTLS is recommended. | NO (listen on `127.0.0.1` by default)
10024 | | Amavisd-new | Used to scan inbound messages, includes spam/virus scanning, DKIM verification, applying spam policy. | NO (listen on `127.0.0.1` by default)
10026 | | Amavisd-new | Used to scan outbound messages, includes spam/virus scanning, DKIM signing, applying spam policy. | NO (listen on `127.0.0.1` by default)
10027 | | Amavisd-new | Used by mlmmj mailing list manager, it bypasses spam/virus/header/banned checks by default, but have DKIM signing enabled. | NO (listen on `127.0.0.1` by default)