How to suspend outgoing emails for all email accounts.

When one hosting account on a mail server starts sending spam, the fastest way to protect the server's reputation is to stop that account's outgoing mail while leaving its incoming mail and website alone. This guide shows how to do that on a DirectAdmin or cPanel server you run yourself, using the tools the panels already provide, and what to do instead if you are on shared hosting.

1. When to suspend outgoing mail

Suspending outgoing mail is an emergency brake, not a fix. Use it when:

• a mailbox password has been guessed or phished and the account is sending spam;
• a hacked script (often an old contact form or a WordPress plugin) is sending mail through PHP;
• the server's IP address is heading for a blocklist and you need the flow stopped before you investigate.

Suspending sending keeps the website up and keeps incoming mail arriving, so the customer loses as little as possible while you clean up. Once the cause is fixed, lift the block.

2. DirectAdmin: block every mailbox of one user

Current DirectAdmin builds ship an Exim configuration that already checks three block lists in /etc/virtual/. You do not need to write your own ACL. We confirmed these lookups in the stock exim.conf of DirectAdmin 1.710 on 23 September 2026; on an older build, check first (see section 3).

To stop all outgoing mail for the DirectAdmin user exampleuser:

Exim reads these files each time it checks a message, so no restart is needed. To lift the block, delete the username's line from the file.

To block one compromised mailbox instead of the whole account:

echo '[email protected]' >> /etc/virtual/blacklist_smtp_usernames

That mailbox can still receive mail and log in to webmail to read it, but it can no longer send through SMTP.

3. Check your DirectAdmin build first

The lists work only if your exim.conf contains the lookups. Check with:

grep -n -E 'BLACKLIST_(USERNAMES|SMTP_USERNAMES|SCRIPT_USERNAMES)' /etc/exim.conf

If the three names are defined and used in the ACLs, you are ready. If nothing comes back, your Exim configuration is out of date. Update it through CustomBuild (./build update followed by ./build exim_conf in /usr/local/directadmin/custombuild) rather than pasting rules into exim.conf by hand: CustomBuild regenerates that file, so manual edits are lost at the next update.

If you do need a custom rule, DirectAdmin's exim.conf includes optional files such as /etc/exim.acl_check_recipient.pre.conf and /etc/exim.acl_check_message.pre.conf. Rules placed there survive updates. See Custom Exim ACL for how to write and test them.

4. cPanel & WHM: suspend outgoing mail for an account

cPanel has this built in, both in WHM and in its API. As root:

# Stop all outgoing mail for the cPanel account "exampleuser"
whmapi1 suspend_outgoing_email user=exampleuser

# Allow it again
whmapi1 unsuspend_outgoing_email user=exampleuser

This covers every mailbox and every script under that account. Incoming mail and the website carry on as normal. Messages that were already in the queue are not removed, so after suspending, review the queue and delete the spam. See Managing the Exim mail queue.

cPanel rebuilds its own exim.conf, so never edit that file directly for this purpose.

5. cPanel: pause sending for one mailbox

On cPanel, an account owner can restrict a single mailbox without root access. In cPanel, open Email Accounts, click Manage next to the mailbox, and look for the outgoing email restriction. It offers:

• Allow: the mailbox sends normally.
• Suspend: outgoing mail from the mailbox is refused.
• Hold: outgoing mail is kept in the queue instead of being delivered, so you can inspect it before it goes anywhere.

This is available to Domain India cPanel customers on shared hosting. On DirectAdmin and Webuzo shared hosting, ask support to block a single mailbox for you.

6. After the block: find and fix the cause

A suspension only buys time. Before you lift it:

For investigation methods, see How to identify outbound spam on a cPanel server and How to investigate email spam abuse problems. If the website itself was hacked, follow the security checklist for a hacked website.

7. Sending limits on Domain India shared hosting

On shared hosting, every account also has a sending limit, which caps the damage a compromised mailbox can do. On our cPanel servers the limit is 200 messages per hour per account; on DirectAdmin it is 1,000 per day. The details are in Do you limit the amount of mail I can send per hour?

8. Running your own mail server on Domain India

A Domain India VPS is self-managed with full root access, so you control Exim, its block lists and its logs. VPS plans do not include cPanel; the VPS page lists the panels offered at checkout. Prices on the card are live and exclude 18% GST.

Spam coming from a mailbox on your shared hosting account? Change its password and open a support ticket. Running your own mail server? Compare VPS plans, or let Business Email handle mail for you.