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## Configuring Mail Services

Your control panel works in cooperation with a mail server, which provides mail services for your domains. After installation the mail server is configured automatically and is ready to serve, however, we recommend that you review the default settings to make sure that they satisfy your needs:

1. Go to Home > Mail Server Settings (in the Server group). The server-wide mail preferences screen will open on the Preferences tab.
2. If you wish to limit the size of an e-mail message that can be sent through your server, type the desired value in kilobytes into the Maximum message size box, otherwise, leave this field blank.
3. If you wish to protect your users from dictionary attacks by not allowing them to use simple passwords, select the Check the passwords for mailboxes in the dictionary option.

   A dictionary attack is when someone tries to find out a valid user name and password by running a program that tries different combinations of dictionary words in different languages. Dictionary attacks can be successful because many users choose their passwords carelessly.

   Note for Windows hosting users: To make this function work properly on Windows platforms, make sure that the Password must meet complexity requirements option is switched on in your server's Local Security Policy settings (the option is located in Start > Administrative Tools > Local Security Policy > Account Policies > Password policy).

4. To protect your server against unauthorized mail relaying or injection of unsolicited bulk mail, select the Enable message submission check box to allow your customers to send e-mail messages through the port 587.

   Also notify your customers that they need to specify in their e-mail programs' settings the port 587 for outgoing SMTP connections, and be sure to allow connections to this port in your firewall settings.

5. Select the mail relay mode.

   With closed relay the mail server will accept only e-mail addressed to the users who have mailboxes on this server. Your customers will not be able to send any mail through your outgoing SMTP server, therefore, we do not recommend closing mail relay.

   With relay after authorization, only your customers will be able to receive and send e-mail through your mail server. We recommend that you leave the authorization is required option selected, and specify allowed authentication methods:

   - POP3 lock time. With POP3 authorization, once a user has successfully authenticated to the POP server, he or she is permitted to receive and send e-mail through the mail server for the specified period of time.
   - SMTP. With SMTP authorization, your mail server requires authorization if the e-mail message must be sent to an external address.

     Note for Windows hosting users: If you do not wish to use relay restrictions for networks that you trust, specify the network IP and mask in the Use no relay restrictions for the following networks: field (e.g., 123.123.123.123/16) and click the icon. To remove a network from the list, click the icon corresponding to the network you wish to remove.

     The relay hosts on the networks in the list are considered not to be potentially operated by spammers, open relays, or open proxies. A trusted host could conceivably relay spam, but will not originate it, and will not forge header data. DNS blacklist checks will never query for hosts on these networks.

   There is also an option to allow open relay without authorization, which, by default, is hidden from the user interface. Opening mail relay without authorization is not recommended because it allows spammers to send unsolicited mail through your server. If you want to set the open relay, log in to the server's file system, locate the file `root.controls.lock` in your Parallels Plesk Panel installation directory (`PRODUCT_ROOT_D/var/root.controls.lock` on Unix and `PRODUCT_DATA_D/var/root.controls.lock` on Windows platforms) and remove the line `/server/mail.php3:relay_open` from this file. The open relay option will show in your control panel.

6. Select the webmail program that should be available to the users.
7. Select the antivirus program that should be used on the server.
8. Select the spam protection option that should be used on the server.
9. Select the mail account name format.

   Selecting the Use of short and full names is allowed option will allow users to log in to their mail accounts by specifying only the left part of e-mail address before the @ sign (for example, username), or by specifying the full e-mail address (for example, username@your-domain.com).

   To avoid possible authorization problems for e-mail users who reside in different domains but have identical user names and passwords, we recommend that you choose the Only use of full mail account names is allowed option.

   Once you have set your mail server to support only full mail account names, you will not be able to switch back to supporting short account names until you make sure there are no encrypted passwords for mailboxes and user accounts with coinciding user names and passwords residing in different domains.

10. Click OK to submit any changes.

    Note: If you wish to set up spam protection systems, such as SpamAssassin spam filter, or protection systems based on DomainKeys, DNS blackhole lists or Sender Policy Framework (SPF), proceed to the section Setting Up Spam Protection.

In this section: Setting Up Spam Protection Setting Up Virus Protection (Linux Hosting) Setting Up Virus Protection (Windows Hosting) Configuring Mailman Mailing List Software (Linux Hosting) Preventing Your Customers From Sending Mass E-mail (Linux Hosting)