Every cPanel account has a default mailbox. The main job of the default account is to deal with emails sent to non-existing email addresses. cPanel’s Default Address section lets you define exactly what should happen with such emails.

About the default mailbox

The default mailbox is created automatically when your cPanel account is set up, and the mailbox can’t be removed. This is because the mailbox does a number of important things.

Bounce (or accept) unrouted emails

For our example.net account we got just one proper email account: info@example.net. Assuming that the DNS is set up correctly emails sent to that email address will be delivered to our inbox. But what happens with emails that are sent to, say, mail@example.net? By default, the email will be purged and the server will fire off a bounce email to the sender. There are other options though, as described below.

Sent emails via scripts

The same goes for emails sent from your website. By default, emails sent via for instance PHP scripts are sent from the default mailbox. In our case the emails would be sent from example@strawberry.active-ns.com. If a receiving mail server bounces one of our emails then the bounce email will be delivered to the default mailbox.

As an aside, if you are using the PHP mail() function then you should really sent email from a proper mailbox – relying on the default mailbox is likely to cause email delivery issues.

Collect system emails

And to give one more example of the type of emails you may find in the default mailbox, by default cron job emails are also sent to the default account.

Configuring the default mailbox

There are two common options for dealing with emails sent to non-existing users, as well as a few advanced options. The common options are:

  • Discard the email. This will purge the email and the sender will receive a bounce email. The default bounce message is “no such person at this address”.
  • Forward the email. This option lets you forward emails to another email address.

cPanel's 'Default Address' interface.

Image: the Default Address interface lets you define how emails sent to non-existing users should be handled.

The default option (discard the email) is sensible. You are likely to find that pretty much all emails sent to non-existing users are spam, so you probably don’t want to forward the emails.

Advanced options

There are a few less common options for dealing with emails sent to the default mailbox. Clicking on the Advanced options link reveals them:

  • The Forward to your system account setting will route all emails to the default mailbox’s inbox without sending a bounce email. This option is not recommended as the sender wouldn’t be notified that the email address doesn’t exist. In effect, emails sent to any user would be accepted, even if the user doesn’t exist. Such a set-up is the dream of spammers.
  • The Discard option does the opposite: it will purge emails sent to non-existing users and not send the sender a bounce email. This option is also not recommended. There are various reasons why genuine emails may be routed to the default address. For instance, the sender may have made a genuine typo. If no bounce email is sent the sender is unlikely to know that the email hasn’t been delivered.
  • Finally, the Pipe to a program option lets you deliver the email to a custom script. If you are a PHP or Perl wizard you can then perform all sorts of magic. In practise, though, this option is usually more trouble than it’s worth.

The advanced options on the Default Address page.

Image: the advanced options.

Configuring multiple domains

If you are hosting more than one domain (i.e. if you got one more addon domains) then you can configure how unrouted mail should be handled for individual domains. The default option is always to discard emails sent to non-existing email accounts. However, you can change this default for any individual domain:

  • Select the domain from the drop-down list.
  • Define how unrouted email should be handled.
  • Click on Change to save the changes.

In other words, you can choose to discard unrouted emails for example.net but forward unrouted emails for example.com. Again, we recommend to always use the discard option, but if you want you can change the default option.