The “Settings” module is located in the “Mail” menu. This module is designed for configuring the mail server and contains three tabs: “Settings”, “Spam protection” and “Address book”.
SMTP/POP3/IMAP port allows you to change the standard ports for receiving and sending emails.
The “SMTP interfaces” and “POP3/IMAP interfaces” fields are intended for specifying the interfaces established on the ICS CUBE, on which the SMTP/POP3/IMAP protocols will work. By default, work is done on all interfaces.
If you select the “Automatically create a permitting rule” flag, the permitting rule will be set in the firewall for SMTP/POP3/IMAP ports. You can go to the list of permitting rules and their settings by clicking on the “Access to the mail server” hyperlink that appears.
The ICS CUBE mail server by default works in the “Not use” mode using the SMTP, POP3/IMAP protocols. We recommend using this mode only on a secure network, since in this mode, hackers can get information about the User's name and password by listening to the channel.
The “May use” mode. If the client software does not support encryption, the password is transmitted over an unencrypted channel, in plain text. If the client software supports encryption, authorization occurs already inside the encrypted connection.
The “Use” mode. In this mode, when users log in via SMTP, POP3/IMAP, or STARTTLS, the password is transmitted only inside the encrypted connection.
Configuration of the “Encryption” block for the “May use” and “Use” modes is described below.
The following settings are necessary for setting various restrictions when sending emails:
Mail messages that were not sent are placed in the queue for resending.
The following settings are necessary for setting different time intervals when sending mail messages again:
In the ICS CUBE you can configure outgoing mail to be sent via a different SMTP server for all messages, except for messages the destination address of which is a local domain or recipient. In order to enable sending of outgoing mail through another SMTP server, it is necessary to enter its address (domain name or IP) in the “Default relay” field and specify the connection port.
The “Use SMTPS” flag is only used for SMTPS connections on port 465. Thus, the flag for sending messages to the destination port 465 is mandatory. When connecting to port 25, the SSL flag should not be set, because encryption of the connection via the STARTTLS extension will be selected automatically, depending on the support of this method for encrypting the connection by the remote party.
If the external SMTP server requires user authentication, you must set the “Use SMTP authentication” flag and specify the user's username and password. Please note that when sending mail messages via SMTP servers yahoo.com / gmail.com and so on, you need to set the “Change sender email” flag, because for these mail servers, the sender's address (FROM header) shall match the user who was logged in, and also set the sender's address in the “Sender email” field.
It allows you to add white and black address lists from which incoming correspondence is allowed or forbidden. When you click on the “Whitelist” button, a new dialog box will open, where you can add: IP-address, domain name, network (including the one created in the ICS CUBE), mail server (for example, @google.com), mailbox. ICS CUBE will always accept emails without checking grey lists and checking the correspondence of forward and reverse DNS records, as well as without authorization. Attention! Only senders who are truly trustworthy should be included in this list.
When you click on the “Blacklist” button, a new dialog box will open, where you can add IP-address, domain name, network, mail server (for example, @google.com), mailbox. ICS CUBE will not accept emails from them.
This block allows you to select a mail domain that is set up on the ICS CUBE during client authorization. For example, the ICS CUBE has a domain.local mail domain, and the user from this domain receives the “usermail” mailbox name. Then when you select “domain.local”, the user when accessing the ICS CUBE mail server via the mail client or via the web interface in the “User name” field can only specify “usermail”, and not firstname.lastname@example.org.
This block allows you to move the mail storage to a separate hard drive. By default, mail is stored in the primary system partition (where the ICS CUBE is installed). If you change the storage location of your mail, all emails will be copied from the current hard drive to the new one. You can track the progress of copying mail from drive to drive in the Menu – Maintenance – System – Tasks. If the new hard drive already contains files with mail, then copying will not be performed (only for ICS CUBE 5.1.7 and higher).
It allows you to specify the host name that will be passed in the SMTP HELO or EHLO command to the remote party when sending an email.
It allows you to set a list of standard folders that are created in the mailbox. If necessary, you can change the composition.
This block includes checking incoming and outgoing messages for viruses in them. If the result is positive, the recipient will receive a message about the results of this check instead of the email itself, and the email itself will be attached to the message. Anti-virus check (Clamav, Kaspersky Antivirus, you must perform the appropriate configuration to use the antivirus) is activated by setting the appropriate flag next to the name of the antivirus.
More information about DKIM-signatures can be found here: https://en.wikipedia.org/wiki/DomainKeys_Identified_Mail
When the flag is set, it enables the DLP module checking of emails (by setting the flag in Menu - Security - DLP - Settings - the “Use DLP for mail” flag), provided that the DLP module is correctly configured and that it is working.
If this flag is set, messages sent from the ICS CUBE mail server will have UTF-8 subject encoding.
This flag enables / disables support of UTF-8 encoding when receiving and sending messages.
In the “Spam protection” tab, you can configure servers that contain black lists, as well as configure the operation mode of the grey list in the ICS CUBE.
This block allows you to add / remove hosts that contain DNSBL blacklists. These lists are used to fight spam. When receiving an email, the ICS CUBE mail server addresses all the hosts specified in this list and checks them for the IP-address of the sender from which it receives the message. If there is no response at all or at least a positive response from one of the hosts, ICS CUBE considers that an attempt is being made to receive spam messages. The message is not received, and the sender's server gets a 5xx error (fatal error).
This block is intended for installation of automatic spam blocking system. When you set the “Use grey lists” flag, the ICS CUBE will track the behavior of mail servers that send messages to the ICS CUBE. You can read about the blocking methodology at the following address: https://en.wikipedia.org/wiki/Greylisting_(email)
Grey lists are set up according to three parameters - the “ignore resending” field in seconds (it is assumed that a reliable mail server will not send an email again at this time); the “await resending” field is indicated in hours (it is assumed that the email should arrive not later than the specified time); the “keep in white list” field is indicated in days (it is assumed that the mail server that has passed the scan will not go through it for a certain number of days).
The “Address book” tab defines the parameters of the address book of the ICS CUBE mail server for client programs of the users. Here you can define the port on which LDAP is running, configure the Base DN parameter (LDAP search base, you can specify several of them using semicolons), enable or disable the use of the address book, and set the “Use ICS Address Book” flag.
Please note that this flag allows you to send the address book to all mail clients, but if this flag is set, it is possible not to transfer the address book to Roundcube (the corresponding settings are made in the Menu - “Mail” - “Web-mail” - the “Settings” tab).