Introduction

Email remains one of the most essential services for businesses and individuals alike, powering everything from customer communication to order confirmations and internal collaboration. While domain-level email accounts allow you to control specific mailboxes, server-wide mail settings determine how your entire Plesk server handles email services.

These global settings impact spam filtering, relay rules, outgoing limits, and how your server interacts with external mail systems. As an administrator or webmaster, properly configuring them is essential for ensuring reliable mail delivery, preventing abuse, and securing your server against spam or blacklisting.

In this tutorial, we’ll walk you through how to access and manage server-wide mail settings in Plesk so that you can fine-tune email functionality across all domains.

Let’s get started!

Accessing Server-Wide Mail Settings

To start managing your server-wide mail settings in Plesk, please make sure you have logged in to your Plesk control panel. To do that, please type in your IP address, hostname, or domain name inside your browser search bar and add “:8443” at the end. It should look something like: https://yourdomain.com:8443. By doing that, you will be prompted by a login form requiring your username and password.

Once logged in, Plesk will automatically display the “Websites & Domains” page, which serves as the index page upon login, unless configured otherwise or if no domains or websites have been added.

To access the Mail Server Settings page, please point your attention to the left side menu and from there, please click on the “Tools & Settings”.

Once you perform the action above, you will be redirected to the Tools & Settings page, which will seem overwhelming at first, simply because it contains a lot of tools.

From the pool of available settings, please select the “Mail Server Settings” link, located under the “Mail” category.

Upon clicking on the “Mail Server Settings” link, you will be redirected to the page that will contain all available server-wide email settings. Please continue with this tutorial to understand what they do and how they work.

Configuring General Mail Settings

In the “Mail Server Settings” page, you can adjust how the server processes incoming and outgoing mail. Some of the key options include the following.

General options

Under these settings, you will see the currently installed mail server and IMAP/POP3 servers. 

• Enable mail management functions in Plesk: Please check this box to activate mail services for the server. If disabled, Plesk will not handle mail at all.

The default ones that Pleks installs by default are Postfix (mail server) and Dovecot (IMAP/POP3 server). You may change these if you prefer from the “Add and Remove Product Components” functionality, which we will cover in a separate tutorial. 

• Maximum message size - Please use this field to type in the maximum message size of the emails that you can send from the Plesk server. You can completely disable it and make this unlimited, or just use the default 10000 value. We recommend increasing this by roughly 30-40% if you or your users are planning on using attachments.

• Maximum number of connections (IMAP, POP3, IMAP over SSL/TLS, or POP3 over SSL/TLS) - Please use this field to type in the maximum number of mail users that can be logged in at the same time.

• Maximum number of connections for a user per IP address - Please use this field to enter the maximum number of connections (IMAP, POP3, IMAP over SSL/TLS, or POP3 over SSL/TLS) allowed for a mail user from each IP address.
• Outgoing mail mode - Please use the radio buttons here to set the outgoing mail mode.

• The first option is Send from domain IP addresses - which, as clearly stated, will send the message from the domain’s IP address.

• The second option is to send from domain IP addresses and use domain names in SMTP greeting, which will also send the message from the domain’s IP address, but will also use the domains in question in the SMTP greetings.

• Enable SMTP service on port 587 on all IP addresses - Please use this checkbox to enable SMTP service on port 587 (TLS port) on all IP addresses.

• Enable email subaddressing - Please use this checkbox to enable email subaddressing. When enabled, it allows you (and your users) to use plus addressing (also called subaddressing) with your email addresses. All of these messages will still be delivered to [email protected] but the part after the plus sign (shopping, newsletter, project) can be used for filtering, sorting, or identifying where the email address was used.

• Enable mailbox quota warning - Please use this tickbox to enable mailbox quota warning notifications to mail users, once it has reached 95%.

• Fix the incorrectly set sender for outgoing mail - Please use this checkbox to enable or disable automatic email headers setting and sender envelope addressing for outgoing mail from domains to reduce chances of being treated as spam. 

Mail autodiscover

Under this category, you will be able to configure your mail autodiscover settings

• Enable mail autodiscover - Please use the tickbox to enable this feature and reconfigure all the domains on the Plesk server to have autodiscover turned on.
• Custom domain name - Please use this text field to specify a custom domain name that will be used as incoming and outgoing mail servers for mail autodiscover configuration. Please also note that the domain name must be secured with a valid SSL/TLS certificate in order for this setting to work.
• Reconfigure autodiscover DNS records - Please use this checkbox to enable this feature and allow reconfiguration for all the domain names' autodiscover DNS records that have autodiscover turned on.

Relay options & Limitations on outgoing email messages

Under these categories, you will be able to configure your mail relay options and set limitations on outgoing email messages

• Relaying - Please use the radio buttons to configure the Plesk server’s relaying behaviour:
• Closed - Please select this option if you want to disable relaying completely.
• Authorization is required. Please select this option and then use the tick box below to enable relaying for either IMAP or SMTP.
• Turn on limitations on outgoing email messages - Please check this tickbox to enable limitation configuration for outgoing emails.
• Count the number of recipients instead of messages - This setting can be selected only if the previous one is selected. It will enable a mode that counts the number of recipients rather than messages when limiting Outgoing mail and counting statistics. For example, one message sent to 10 recipients will be counted as ten messages.
• Default limit on outgoing messages from a mailbox (per hour) - Please use this text field to set the default limit on outgoing messages from an email box per hour.
• Default limit on outgoing messages from a domain (per hour) - Please use this text field to set the default limit on outgoing messages from a domain address per hour.
• Default limit on outgoing messages from a subscription (per hour) - Please use this text field to set the default limit on outgoing messages from a subscription per hour. A subscription can be considered a web hosting package within Plesk.
• Allow users and scripts to use Sendmail. Please check this tickbox to enable scripts to send email messages (on behalf of the subscription's system user) using Sendmail. This will be available even if the limits for a mailbox and domain are exceeded. The maximum number of messages that can be sent through Sendmail will be defined by the limit for an entire subscription. This setting does not allow scripts to use Sendmail server-wide, but it acts as a default setting for service plans and subscriptions.
• Show reports based on statistics for the last - Please use this drop-down menu to show reports and alerts on the index page about attempts to exceed limits on outgoing mail during the specified period.
• Send an email notification every - Please use this drop-down menu to enable notifications that provide statistics on attempts to exceed limits on outgoing mail during the specified period.

DMARC, DKIM, and SPF spam protection

Under these categories, you will be able to configure your DMARC, DKIM, and SPF DNS record settings and spam protection settings.

• Enable DMARC to check incoming mail - Please use the checkbox to enable DMARC check for all incoming emails. This option is available when DKIM and SPF are switched on.

• Allow signing outgoing mail - Please use this tickbox to enable DKIM signing for outgoing emails. 

• Verify incoming mail - This option cannot be switched off while DMARC is switched on for incoming mail. If you would like to switch this off, please disable the DMARC check for inbound emails.

• Enable SPF spam protection to check incoming mail - This option cannot be switched off while DMARC is switched on for incoming mail. If you would like to switch this off, please disable the DMARC check for inbound emails.

• SPF checking continues when there are DNS lookup problems - Please use this checkbox to enable or disable SPF checks even when there are DNS lookup problems. This option is cleared if it has no effect in the current checking mode.

• SPF checking mode - Please use this drop-down menu to select the SPF checking mode behaviour. The message can be rejected depending on the selected checking mode and the checking result.

• SPF local rules - Please use this text field to set the custom SPF rules you define locally on your server. They are applied in addition to the official SPF record of the sender’s domain. They can also override missing/weak SPF records from the sender.

• SPF guess rules - Please use this text field to set guest rules that are used when the sender’s domain has no SPF record at all. Your server then applies these “guessed” defaults to decide if mail should be accepted.

• SPF explanation text - Please use this text field to set a custom rejection message shown when an incoming email fails SPF. It can include macros to reference the sender IP, domain, etc. It’s useful for giving meaningful feedback to mail admins on the sending side.

Spam protection & Extra auto-reply headers

Under these settings, you can configure additional headers for any auto-reply messages sent and tweak your spam protection settings on your Plesk server.

• Turn on spam protection based on DNS blackhole lists - Please use this checklist to enable spam protection based on DNS blackhole lists. Plesk’s DNSBL feature checks sender IPs against anti-spam blocklists during the SMTP handshake. If a sender is blacklisted, mail is rejected or marked, reducing spam before it reaches users' inboxes.

• DNS zones for DNSBL service - Please use this text field to add entries, separating them with a semicolon, for example: 'dnsbl.domain.com'.
• Extra Headers - Please use these text fields to define custom mail headers that will be added to all outgoing messages from that mailbox. These headers are not limited to auto-replies; they apply to all emails sent from that account.

Applying and Saving Changes

Finally, when you are done configuring all of the settings regarding the mail server, please click on the “Apply” or “Ok” buttons located at the bottom of the page. Clicking on the “Ok” button will save the settings and redirect you back to the “Tools & Settings”, while pressing the “Apply” button will apply the settings, and you will remain on the settings page. 

Antivirus Settings

To prevent malicious attachments from reaching users, you can enable antivirus scanning for incoming and outgoing mail. Depending on your Plesk configuration, options may include:

• Sophos Anti-Virus for Servers
• Premium Antivirus for Servers
  
  

Once enabled, these services will scan messages across all mailboxes on the server and will quarantine those that it detects are malicious. Of course, there are other popular options, such as Imunify360 and SpamExperts, which you can use; however, these are paid options, as opposed to the previously mentioned and recommended ones by Plesk.

Configuring Black & White lists

Black and white email lists are lists inside which you add domains or networks (IP ranges) that will be allowed or denied to send/receive emails. To access these settings, please navigate to the 

Black Lists

From the “Mail Server Settings” page, please click on the “Black Lists” tab.

Performing this action will redirect you to the page, allowing you to add domains to the server’s black list. To do that, please click on the blue “Add Domain” button right in the middle of the page. 

After performing this action, a pop-up window from the left side will show up and will contain a text field, where you can type in the domain you want to add to the block list.

Underneath, you will see an “Add one more” link, which will increase the number of text fields on the pop-up window and allow you to add more domains to the black list. Once you are finished adding the domains you want to the blacklist, please click on the “Ok” button located on the bottom left side of the pop-up window.

White Lists

To access the White Lists feature, from the “Mail Server Settings” page, please click on the “White Lists” tab.

Performing this action will redirect you to the page, allowing you to add networks (IP ranges) to the server’s whitelist. To do that, please click on the blue “Add Network” button right in the middle of the page. 

After performing this action, a pop-up window from the left side will show up and will contain a text field, where you can type in the IP range you want to add to the white list.

Underneath, you will see an “Add one more” link, which will increase the number of text fields on the pop-up window and allow you to add more IP ranges to the white list. Once you are finished with adding the desired IP ranges to the whitelist, please click on the “Ok” button located on the bottom left side of the pop-up window.

Smarthost Options

Relay settings control whether your server sends mail directly to recipients or forwards it through another mail server. This setting is also known as a smart host. To access this feature, from the “Mail Server Settings” page, please click on the “Smarthost” tab.

Important: If you configure outgoing emails with a smarthost, you need to update the SPF and other related DNS records in the DNS template and in the DNS zones of existing domains manually. This is essential to prevent validation errors for outgoing emails through the smarthost. 

Let’s explore all the available options there and explain what they do so you can get a better understanding.

• Send users' mail via a smarthost - Please use this checkbox to enable the smarthost options for your Plesk server. Unless this is ticked, the rest of the options will either be locked or will have no effect when configured.

• Hostname or IP address - Please use this text field to type in the mail relay (smarthost) you want to use. This can be a domain (e.g., smtp.gmail.com, relay.sendgrid.net) or an IP (e.g., 192.0.2.10). Plesk will direct all outgoing mail through this server. To disable MX or SRV lookups, put the hostname or IP address in square brackets, for example, “[stmp.gmail.com]” Corresponding this this text field, there will be a button that tests whether Plesk can successfully connect to the smarthost with the settings you entered. It verifies hostname resolution, port availability, and authentication; thus, please use it if you want to test the connection to the added IP or hostname.

• Port - Please use this text field to set the port number used to connect to the smarthost’s SMTP service. The typical ports are 25 (non-ssl SMTP port); 465 (SSL SMTP port) and 587 (STARTTLS SMTP port).

• Authentication required - Please use this checkbox to enable authentication for your smarthost, which will require login credentials. If disabled, Plesk just connects and relays mail without logging in.

• Username - Please use this text field to type in the smarthost authentication hostname.

• Password - Please use this text field to type in the smarthost authentication password. 

• Encrypted connection - Please use the radio button to set how the connection is secured. This option will depend on the provider. If your provider requires this, please select the “Required” option; if not, please choose the “Not Required” option.

Once you are finished with configuring your Smarthost configuration, please either click on the “Ok” or “Apply” buttons at the bottom of the page. Clicking on the “Apply” will save your settings and will refresh the page, while clicking on the “Ok” will redirect you back to the “Tools & Settings” page.

Conclusion

Server-wide mail settings in Plesk give administrators complete control over how the mail system operates. By adjusting general options, outgoing limits, relay configurations, and security policies, you can ensure reliable, secure, and professional email service across all domains hosted on your server.

By following this guide, you’ll be well-equipped to configure and maintain global email settings, keeping your communication systems safe and efficient.