Kennisbank

Overview:

Select the Basic Editor tab in the Exim Configuration Manager interface to modify your server’s Exim configuration settings.

All

This tab displays all available settings. To filter the displayed settings, select a category tab. You can also use the Find text box to search for a specific Basic Editor setting.

ACL settings

These settings limit who can send mail to your server. Use these settings to minimize bandwidth usage, prevent spam, and block emails with a forged sender address (spoofed emails).

Apache SpamAssassin™ reject spam score threshold

This setting sets the spam score that Apache SpamAssassin™ uses to reject incoming messages.

Enter a positive or negative number, which may contain a single decimal point.

This setting defaults to No reject rule by spam score.

Dictionary attack protection

This setting allows you to drop and rate-limit hosts with more than four failed recipients, in order to block dictionary attacks. A dictionary attack is a method whereby a malicious user attempts to guess a password with words in a dictionary.

This setting defaults to On.

Reject remote mail sent to the server’s hostname

This setting allows you to reject messages in which the recipient exists as an address of your server’s primary hostname. In general, the primary hostname, a common target for spammers, should not receive remote mail.

This setting Defaults to Off.

Enable Apache SpamAssassin™ for secondary MX domains

This setting configures Apache SpamAssassin to scan email for domains that exist in the /etc/secondarymx file which users send to the primary mail exchanger.

This setting defaults to On.

Ratelimit suspicious SMTP servers

This setting allows you to rate-limit incoming SMTP connections that violate RFCs. This setting rate-limits mail servers that do not send QUIT, recently matched an RBL, or recently attacked the server. Real mail servers must follow RFC specifications.

This setting defaults to On.

Apache SpamAssassin™: ratelimit spam score threshold

This setting allows you to rate-limit hosts that send spam to your server. When you activate this setting, rate limits delay email from hosts that send you spam. The system activates rate limits when it meets both of the following conditions:

1. A host reaches or exceeds the Apache SpamAssassin score that you enter in the text box.

2. That host exceeds the number of emails that the rate-limit formula specifies. Exim averages rate limits over time. By default, the system uses the following rate-limit formula:

   ratelimit = 1.2 / 1h / strict / per_conn / noupdate

    

This setting defaults to No ratelimiting by spam score.

Ratelimit incoming connections with only failed recipients

This setting allows you to rate-limit incoming SMTP connections that only send email to failed recipients during five separate connection times in the past hour.

This setting defaults to On.

Require HELO before MAIL

This setting allows you to require that incoming SMTP connections send a HELO command before they send a MAIL command.

A HELO is a command that mail servers send before an email, and that specifies the name of the sending domain. Apache SpamAssassin can perform various checks on this information (for example, it can ensure that the domain name matches the IP address that sent the message). This ensures that your server does not receive spam that reports a false domain name.

This setting defaults to On.

Introduce a delay into the SMTP transaction for unknown hosts and messages detected as spam.

This setting configures the SMTP receiver to wait a few additional seconds for a connection when it detects spam messages. Typically, legitimate mailing systems will wait past the delay, whereas spammers do not wait past the delay.

This setting defaults to On.

Do not delay the SMTP connections for hosts in the Greylisting “Trusted Hosts” list

This setting configures the SMTP receiver to not delay any hosts that you add to the list in the Trusted Hosts tab in WHM’s Greylisting Interface (WHM >> Home >> Email >> Greylisting).

This setting defaults to On.

Do not delay the SMTP connections for hosts in the Greylisting “Common Mail Providers” List

This setting configures the SMTP receiver to not delay any hosts that you add to the list in the Common Main Providers tab in WHM’s Greylisting interface (WHM >> Home >> Email >> Greylisting).

This setting defaults to Off.

Require remote (hostname/IP address) HELO

This setting allows you to require that incoming SMTP connections send a HELO command that does not match the primary hostname or a local IP address (IPv4 or IPv6). Enable this setting to block emails with a forged sender address (spoofed emails).

This setting defaults to On.

Require remote (domain) HELO

This setting allows you to require that incoming SMTP connections send a HELO command that does not match your server’s local domains. Enable this setting to block emails with a forged sender address (spoofed emails).

This setting defaults to Off.

Require RFC-compliant HELO

This setting allows you to require that incoming SMTP connections send a HELO command that conforms with the Internet standards in RFC 2821 4.1.1.1.

This setting defaults to On.

Allow DKIM verification for incoming messages

This setting allows you to use DomainKeys Identified Mail (DKIM) verification to verify incoming messages.

This setting defaults to Off.

Reject DKIM failures

This setting allows you to reject email at SMTP time if the sender fails DKIM key validation.

This setting defaults to Off.

Maximum message recipients (soft limit)

This setting allows you to determine the number of recipient addresses your server accepts in a single message.

This setting defaults to No rejection based on number of recipients.

Maximum message recipients before disconnect (hard limit)

This setting allows you to determine the number of recipient addresses that your server permits in a single message before it disconnects and rate-limits a connection.

This setting defaults to No disconnection based on number of recipients.

Access Lists

These settings further limit who sends mail to your server.

Blacklisted SMTP IP addresses

This setting allows you to edit the list of blacklisted SMTP IP addresses. The system does not allow these IP addresses to connect to the SMTP server, and instead drops connections with a 550 error.

Click Edit to modify this setting.

Sender verification bypass IP addresses

This setting allows you to edit the list of IP addresses that the system excludes from SMTP sender verification checks.

Click Edit to modify this setting.

Only-verify-recipient

This setting allows you to edit the list of hosts or IP addresses that the system excludes from all spam checks at SMTP connection time, except recipient verification checks. The system adds any hosts or IP addresses you enter here to the /etc/trustedmailhosts file.

Click Edit to modify this setting.

Trusted SMTP IP addresses

This setting allows you to edit the list of hosts or IP addresses that the system excludes from the following checks at SMTP connection time:

• Recipient verification checks

• Sender checks

  Note:

  These senders must still use an RFC-compliant HELO name if the Require RFC-compliant HELO setting is enabled.

   

• Spam checks

• Relay checks.

  Note:

  The system adds any hosts’ IP addresses that you enter here to the /etc/skipsmtpcheckhosts file.

   

Click Edit to modify this setting.

Backup MX hosts

This setting allows you to edit the list of hosts from which the system permits SMTP connections, regardless of rate limits. Make certain that you properly configure reverse DNS records for any hosts which you enter here.

Click Edit to modify this setting.

Trusted mail users

The Trusted mail users setting allows system administrators to designate certain users as trusted mail users. This setting affects the EXPERIMENTAL: Rewrite From: header to match actual sender setting in the Mail tab. Trusted users can bypass the EXPERIMENTAL: Rewrite From: header to match actual sender setting. The Trusted mail users setting allows the listed users to modify their From: header, and the EXPERIMENTAL: Rewrite From: header to match actual sender setting does not override these changes. Enter the trusted mail usernames or their email addresses, one per line.

Click Edit to modify this setting.

Blocked Domains

This setting allows you to filter your server’s incoming email by region or country.

When you click Manage, a new browser tab will appear with WHM’s Filter Incoming Emails by Domain interface (WHM >> Home >> Email >> Filter Incoming Emails by Domain).

Blocked Countries

This setting allows you to filter your server’s incoming email by domain.

When you click Manage, a new browser tab will appear with WHM’s Filter Incoming Emails by Country interface (WHM >> Home >> Email >> Filter Incoming Emails by Country).

Domains and IPs

These settings change the IP address from which Exim sends mail. When you disable them, Exim will automatically send mail from your server’s main shared IP address. For more information, read our How to Configure the Exim Outgoing IP Address documentation.

This setting defaults to Off.

Send mail from account’s IP address

This setting allows you to automatically send mail for users without a dedicated IP address from a reseller’s main shared IP address. It will not use the server’s main shared IP address. The system will also use the server’s hostname for reseller accounts that share an IP address. If you want to change this, you must use a custom configuration.

This setting defaults to Off.

Use the reverse DNS entry for the mail HELO/EHLO if available

The system will use the server’s IP address as the reverse DNS for all outgoing SMTP connections. This only applies during the HELO/EHLO request.

This setting defaults to ON.

Rebuild Reverse DNS Cache and Update Mail HELO

This setting updates the reverse DNS cache and user domains for mail HELO. This setting only appears when you enable the Use the reverse DNS entry for the mail HELO/EHLO if available setting.

Reference /etc/mailhelo for custom outgoing SMTP HELO

This setting allows you to send a HELO command based on the domain name in the /etc/mailhelo file. For more information, read our How to Configure the Exim Outgoing IP Address documentation.

This setting defaults to Off.

Reference /etc/mailips for custom IP on outgoing SMTP connections

This setting allows you to send outgoing mail from the IP address that matches the domain name in the /etc/mailips file. For more information, read our How to Configure the Exim Outgoing IP Address documentation.

This setting defaults to Off.

Filters

These settings allow you to select and configure filters that can block spam and potentially dangerous attachments.

System Filter File

Use this setting to enable or disable Exim’s system filter file, which the system stores in the /etc/cpanel_exim_system_filter file. You can also choose to specify and customize another Exim system filter file.

This setting defaults to /etc/cpanel_exim_system_filter.

Attachments: Filter messages with dangerous attachments

Select this setting to filter email messages that contain potentially dangerous attachments. The system filters the following file extensions:

.ade
.adp
.bas
.bat
.chm
.cmd
.com
.cpl
.crt
.eml
.exe
.hlp
.hta
.inf
.ins
.isp
.js
.jse
.lnk
.mdb
.mde
.msc
.msi
.msp
.mst
.pcd
.pif
.reg
.scr
.sct
.shs
.url
.vbs
.vbe
.wsf
.wsh
.wsc

This setting defaults to On.

Apache SpamAssassin™: Global Subject Rewrite

Select this setting to prefix the Subject header with information from the X-Spam-Subject header and omit the X-Spam-Subject header.

This setting defaults to On.

Apache SpamAssassin™: bounce spam score threshold

Select this setting to define the spam score that Apache SpamAssassin uses to bounce incoming messages. Enter a positive or negative number, which may contain a single decimal point. For more information, read the Apache SpamAssassin documentation.

This setting defaults to No bouncing by spam score.

Apache SpamAssassin™: X-Spam-Subject/Subject header prefix for spam emails

Select this setting to use the default X-Spam-Subject header prefix for spam email or to enter a custom prefix.

This setting defaults to ***SPAM***.

Mail