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  4. Tweak Settings — Mail
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Tweak Settings — Mail

Valid for versions 112 through 114

Version:

110

112

116

118

120

124

Last modified: October 10, 2024

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Note:

Your hosting provider can enable or disable this interface for resellers in WHM's Edit Reseller Nameservers and Privileges interface (WHM >> Home >> Resellers >> Edit Reseller Nameservers and Privileges).

The Mail section includes the following settings:

Setting Description Values Default
Max hourly emails per domain This setting specifies the maximum number of emails that each domain can send per hour. The system only enforces email send limits on remote email deliveries.
Note:
  • This setting does not appear if you disable the Exim Mail Server service in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • This setting does not function if you disable the Eximstats driver in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • This setting does not override the Maximum Hourly Email by Domain Relayed and Maximum percentage of failed or deferred messages a domain may send per hour settings.
  • Minimum value: N/A
  • Maximum value: N/A
 Unlimited
Number of emails a domain may send per day before the system sends a notification. This setting specifies the number of emails per day that a domain can send before the system sends a notification.
  • To count each account’s outbound emails, this feature uses the TailWatch process to monitor a rolling 24-hour window of hourly logfiles. When a new hour begins, the system deletes the oldest hour’s logfile.
  • The system counts outbound mail from subdomains and addon domains separately from their parent domain.
    Note:
    This setting does not function if you disable the Eximstats driver in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • Minimum value: N/A
  • Maximum value: N/A
 Unlimited
The mailbox storage format for new accounts This setting specifies the storage format for new accounts’ mailboxes. Accounts that you restore or transfer to your server will retain their original mailbox format. For more information about storage formats, read Dovecot’s dbox and maildir documentation.
  • mdbox — An updated format that stores multiple messages in a file and uses index files for message flags and keywords.
  • maildir — A format that stores folders as separate directories and messages as individual files. The maildir format uses more inode resources than the mdbox format.
 maildir
Initial default/catch-all forwarder destination This setting specifies the initial forwarding destination for new accounts’ default (catch-all) email addresses. The default address handles email that nonexistent users on your server’s domains receive. Because a domain may receive a large number of spam messages for nonexistent users, if you choose to process this mail your server may use more resources. cPanel users can modify this forwarding destination in cPanel’s Default Address interface (cPanel » Home » Email » Default Address).
  • System account — The system forwards unroutable mail to the cPanel user’s system default email account. If you select this setting, this account collects spam.
  • Fail — The system discards the message and sends a notification to the sender. Select this setting if you receive email attacks.
  • Blackhole — The system accepts the message, discards it, and does not notify the remote SMTP server. We recommend that you do not use this setting because it violates SMTP’s RFC 5321.
 System account
Mail authentication via domain owner password This setting specifies whether to allow the use of the website owner’s password to access any email address that the owner created within the account. The Single Sign On system generates a temporary user to access a cPanel account and its email accounts as the account owner. This means that if you log in to any email account through the cPanel interface, you do not have to enter a password.
  • On — Allow.
  • Off — Don’t allow.
 Off
Include mailman in disk usage calculations This setting specifies whether cPanel’s disk usage calculations include Mailman mailing lists.
  • On — Include.
  • Off — Don’t include.
 On
Email delivery retry time This setting specifies the number of minutes that your mail server waits before it attempts to redeliver a message after delivery failure.
Note:
This setting does not appear if you disable the Exim service in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • Minimum value: N/A
  • Maximum value: N/A
 15 m
Track email origin via X-Source email headers This setting specifies whether to track the origin of messages that users send through your mail server.
  • This feature adds X-Source headers to email messages.
  • This feature requires Exim version 4.34 or later.
Note:
This setting does not appear if you disable the Exim service in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • On — Track.
  • Off — Don’t track.
 On
The percentage of email messages (above the account’s hourly maximum) to queue and retry for delivery. This setting specifies whether to queue outgoing messages for later delivery after a domain reaches its limit for outgoing messages per hour. For example, with the default value of 125%, after the domain reaches its hourly limit Exim queues any additional messages, up to 125% of the Max hourly emails per domain value. After the account reaches 125% of the Max hourly emails per domain value, any additional outgoing messages will fail.
  • To force the failure of all outgoing messages after the domain reaches its limit, set this option to 100.
Note:
  • This setting does not appear if you disable the Exim Mail Server service in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • This setting does not function if you disable the Eximstats driver in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • Minimum value: 100
  • Maximum value: 10,000
 125%
Monitor the number of unique recipients per hour to detect potential spammers. This setting configures the system to monitor the number of emails to unique recipients that each individual email user sends. If this number exceeds the value of the Number of unique recipients per hour to trigger potential spammer notification setting, the system will send a notification.
Note:
This setting does not function if you disable the Eximstats driver in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • On — Monitor.
  • Off — Don’t monitor.
 On
Select the action for the system to take on an email account when it detects a potential spammer. The system automatically takes this action on every email account that it detects as a potential spammer.
To release or delete outgoing mail held in the queue, perform the following actions in cPanel’s Email Accounts interface (cPanel » Home » Email » Email Accounts):
  1. Click Manage Suspension.
  2. Select Allow for the Send option.
  3. If applicable, click Delete messages from the mail queue to remove any queued messages.
  4. Click Save.
Note:
This setting does not function if you disable the Eximstats driver in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • Take no action — Do not perform any action on the email account.
  • Hold outgoing mail — Hold all outbound messages in a queue for the email account.
  • Reject outgoing mail — Block all outbound email for the email account.
 Take no action
Number of unique recipients per hour to trigger potential spammer notification. This setting specifies the number of emails sent by any email account in one hour that will cause the system to send an alert notification. This setting does not count emails sent by Mailman toward the limit. It affects the Select the action for the system to take on an email account when it detects a potential spammer option.
Note:
This setting does not function if you disable the Eximstats driver in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • Minimum value: N/A
  • Maximum value: N/A
 500
Count mailman deliveries towards a domain’s Max hourly emails. This setting allows you to specify whether to count messages to Mailman mailing lists against an account’s Max hourly emails per domain limit.
Note:
  • If you enable this setting, mailing-list subscribers may not receive all list messages.
  • This setting does not function if you disable the Eximstats driver in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • On — Count.
  • Off — Don’t count. Set this value to Off to accommodate users with large Mailman mailing lists.
 Off
Maximum percentage of failed or deferred messages a domain may send per hour This setting allows you to specify a maximum percentage of failed or deferred messages that your domain may send per hour. The system uses this setting in conjunction with the Number of failed or deferred messages a domain may send before protections can be triggered setting. Your server does not temporarily block outgoing mail from a domain until the domain meets both settings’ requirements. For more information, read our How to Prevent Spam with Mail Limiting Features documentation.
Note:
  • This setting does not appear if you disable the Exim Mail Server service in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • This setting does not function if you disable the Eximstats driver in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
Your server temporarily blocks outgoing mail from a domain if both of the following conditions are true:
  • The percentage of failed or deferred messages, out of the total number of sent messages, is equal to or greater than the specified percentage.
  • The domain has sent at least the number of failed or deferred messages that the Number of failed or deferred messages a domain may send before protections can be triggered setting specifies.
The system examines all outgoing and local mail over the previous hour to determine whether these conditions are true. If only one of these conditions is true, the system does not block outgoing mail.
  • Minimum value: 1
  • Maximum value: 100
 Unlimited
Number of failed or deferred messages a domain may send before protections can be triggered This setting specifies a number of failed or deferred messages that a domain can send before the system blocks outgoing mail. Your server temporarily blocks outgoing mail from a domain if both of the following conditions are true:
  • The domain sends at least this number of failed or deferred messages.
  • The percentage of failed or deferred messages (out of the total number of sent messages) is equal to or greater than the percentage that the Number of failed or deferred messages a domain may send before protections can be triggered setting specifies.
The system examines all outgoing and local mail over the previous hour to determine whether these conditions are true. If only one of these conditions is true, the system does not block outgoing mail.
  • For more information, read our Service Manager documentation.
  • The system uses this setting in conjunction with the Maximum percentage of failed or deferred messages a domain may send per hour setting. Your server does not temporarily block outgoing mail from a domain until the domain meets both settings’ requirements.
Note:
  • This setting does not appear if you disable the Exim Mail Server service in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • This setting does not function if you disable the Eximstats driver in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • Minimum value: N/A
  • Maximum value: N/A
 5
Restrict outgoing SMTP to root, exim, and mailman (FKA SMTP Tweak) This setting redirects outgoing SMTP connections to the local mail server and allows only the root, exim, and mailman users to make direction connections. If you enable this setting, scripts and email users must use the sendmail binary to send mail and cannot use direct socket access.
  • On — Redirect.
  • Off — Don’t redirect.
 On
Prevent “nobody” from sending mail This setting denies the nobody user the ability to send mail to a remote address. PHP and CGI scripts generally run as the nobody user. To use a PHP or CGI script to send mail, enable the suEXEC or mod_php modules in your Apache configuration.
  • On — Deny the nobody user.
  • Off — Allow the nobody user to send mail.
 On
Allow users to relay mail if they use an IP address through which someone has validated an IMAP or POP3 login within the last hour (Pop-before-SMTP) This setting allows users who authenticated against the POP3 or IMAP service in the last 30 minutes to send emails through SMTP again without the need to reauthenticate.
Note:
  • An open email relay on an IP address poses a security risk. We recommend that you do not enable this option because it can compromise your users’ privacy and strongly recommend that you use SMTP authentication instead.
  • This setting does not appear if you disable the Exim or RecentAuthedMailIpTracker services in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • On — Allow users to relay mail.
  • Off — Don’t allow users to relay mail.
 Off
Add X-PopBeforeSMTP header for mail sent via POP-before-SMTP This setting requires the mail server to append a list to the X-PopBeforeSMTP headers of all of that user’s outgoing messages. This list contains all of the email addresses that a user checks with POP before SMTP.
  • POP before SMTP is an email protocol that allows users to check email from different IP addresses without the need to log in repeatedly.
Note:
  • We recommend that you do not enable this setting because it can compromise your users’ privacy.
  • This setting requires Exim 4.34 or later and does not appear if you disable the Exim service in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • You must set the Allow users to relay mail if they use an IP address through which someone has validated an IMAP or POP3 login within the last hour (Pop-before-SMTP) setting to On to toggle this setting.
  • On — Require an appended list.
  • Off — Don’t require an appended list.
 Off
Enable BoxTrapper spam trap This setting allows you to enable BoxTrapper, a spam prevention system that uses blacklists, whitelists, and ignore lists, and an automated response-verification system.
Note:
This setting does not appear if you disable the Exim service in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • On — Enable BoxTrapper.
  • Off — Disable BoxTrapper.
 On
Enable Email Archiving support This setting enables email archiving support. Email archiving maintains a copy of each email that your server sends or receives. The server immediately archives an email when it receives the message.
  • This action takes place before the system applies any filters to the message, which means that the system archives both spam and non-spam messages.
    Note:
    This setting does not appear if you disable the Exim service in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • On — Enable email archiving. If you enable this setting, the amount of disk space that mail uses will double.
  • Off — Disable email archiving.
 Off
Enable Mailman mailing lists This setting enables Mailman on your server. Mailman is third-party software that manages mailing lists.
Note:

The system does not start the Mailman service until the server hosts at least one mailing list.
  • On — Enable Mailman.
  • Off — Disable Mailman.
 On
Enable Roundcube webmail This setting enables the Roundcube webmail client. Webmail allows cPanel users to access their email accounts with an internet connection and a web browser.
  • On — Enable Roundcube.
  • Off — Disable Roundcube.
 On
Enable Apache SpamAssassin™ spam filter This setting enables Apache SpamAssassin, a spam filtration program that scores incoming email and checks that score against a predefined limit. If the spam score exceeds this limit, the server takes the action that the domain owner specified in cPanel’s Spam Filters interface (cPanel » Home » Mail » Spam Filters). You can discard mail or place it in a spam folder.
Note:
  • If you make changes to Apache SpamAssassin’s configuration, you must run the /usr/local/cpanel/3rdparty/bin/sa-compile script for your changes to take effect.
  • This setting does not appear if you disable the Exim service in WHM’s Service Manager interface (WHM » Home » Service Configuration » Service Manager).
  • On — Enable Apache SpamAssassin.
  • Off — Disable Apache SpamAssassin.
 On
Enable Apache SpamAssassin™ Spam Box delivery for messages marked as spam (user configurable) This setting enables Apache SpamAssassin’s spam box feature. The spam box receives incoming mail that Apache SpamAssassin marks as spam. This is useful for users who receive a message that the system falsely flags as spam.
  • On — Enable spam box.
  • Off — Disable spam box.
 On
Prefix “mail.” onto Mailman URLs This setting specifies whether the system should prefix Mailman URLs with mail (for example, http://mail.domain.com/mailman).
Note:

If you set this value to On, this setting overrides any custom URL in your Mailman configuration.
  • On — Add the prefix.
  • Off — No prefix.
 Off
Default user-defined quota value for new email accounts This setting defines the default quota that appears in cPanel’s Email Accounts interface (cPanel » Home » Mail » Email Accounts).
  • Minimum value: N/A
  • Maximum value: 4,294,967,296 MB (4 Terabytes)
 32768 MB
Default quota option for new email accounts This setting defines the preselected quota option in cPanel’s Email Accounts interface (cPanel » Home » Mail » Email Accounts).
  • Unlimited — Unlimited quota.
  • User-defined — A user-defined quota.
 User-defined