Question
Can I limit the number of recipients an inbound message contains?
Answer
By default, the option to limit the number of recipients for inbound mail is disabled on cPanel servers.
If you want to set a specific limit to the number of addresses that can be included in an inbound email message you can set this in WHM using the Exim Configuration Manager.
In the Basic Editor under the ACL Options, you will see two options:
Maximum message recipients (soft limit) (Minimum: 1; Maximum: 100)
- Reject any recipient addresses after this number have been specified for a single message. NOTE: The RFCs specify that SMTP servers should accept at least 100 RCPT commands for a single message.
Maximum message recipients before disconnect (hard limit) (Minimum: 1; Maximum: 100)
- Disconnect and ratelimit any connection that specifies more than this number of recipients for a single message. NOTE: The RFCs specify that SMTP servers should accept at least 100 RCPT commands for a single message.
You will want to set both to the custom values of your choice. Then scroll to the bottom of the editor page and click on Save.
Please note, that these settings do not limit or prevent the number of email addresses that can be included in an email sent from any accounts on your cPanel server.