Setting up Email Spam Filtering

Last updated: 2 November 2026

Email Spam Filtering checks your email in the cloud before it reaches you, and can check the email you send as well. This article explains how to switch it on for your domain and how to use it day to day.

What you've bought

• Incoming filtering checks every message sent to your domain and holds back spam and viruses before they reach your mailboxes.
• Outgoing filtering checks the email you send, so a compromised account or infected computer can't damage your domain's reputation with other mail servers.
• The Incoming & Outgoing bundle includes both.

Each service covers one domain. If you have two domains, you need a service for each.

Open the spam panel

1. Sign in to the client area and go to My Services.
2. Click your Email Spam Filtering service.
3. Click Log In (under Actions). The spam panel opens in a new tab, already signed in to your domain.

Everything below is done in that spam panel, apart from the DNS changes.

Switching on incoming filtering

Incoming filtering works by sending your domain's email to the filter first. The filter then passes the clean mail on to wherever your mailboxes really are. So there are two things to set, in this order.

1. Check where clean mail is delivered

In the spam panel, open Incoming › Destinations (the server that clean mail is passed on to). It must point to the server that holds your mailboxes:

• Your mailboxes are with our Professional Email: the route should be our email servers, mx001.cloudus.rs.oxcs.net (and mx002 to mx004), port 25.
• You run your own mail server, or use another provider: the route should be your mail server's name or public IP address, port 25. If you use Microsoft 365 or Google Workspace, use the MX address they give you.

When the service is set up, the panel fills this in from your domain's current MX record, so it's usually right already. Check it before you go on to step 2: if it's wrong, mail is filtered and then delivered to the wrong place, or not at all.

2. Change your MX records

Your domain's MX records tell the world where to send your email. Remove your existing MX records and add these three instead:

• If your domain uses our nameservers, you can change them yourself in the client area: see Managing your DNS records.
• If your DNS is managed somewhere else (for example by your web designer or another provider), change them there, or ask whoever looks after it.

DNS changes can take a few hours to reach everyone. During that time some mail still arrives the old way, which is normal: nothing is lost.

Switching on outgoing filtering

Outgoing filtering works by sending your email through the filter instead of straight from your own mail server.

1. In the spam panel, open Outgoing › Manage users and add a user. Choose Authenticating IP if you run your own mail server with a fixed IP address (no password needed), or Authenticating User or Authenticating Domain to send with a username and password. Keep any password safe.
2. On the mail server or app that sends your email, set the outgoing server (sometimes called the "smarthost" or "relay") to:
   • Server: smtp.antispamcloud.com
   • Port: 587, with STARTTLS (465 also works; avoid 25)
   • Authentication: the username and password from step 1 (not needed if you added your server's IP address)
3. Update your SPF record so receiving servers know the filter is allowed to send for you: add include:spf.antispamcloud.com to your existing SPF record (don't create a second one). See Managing your DNS records.

Running your own mail server? Set the smarthost in your mail server's settings, so everything it sends goes through the filter. The supplier's documentation has steps for common mail servers such as Exchange, Postfix and cPanel.

Using our Professional Email? Outgoing filtering doesn't apply: Professional Email sends through its own servers, and it can't be routed through another filter. Incoming filtering works with Professional Email as described above.

Using it day to day

The quarantine

Messages the filter thinks are spam are held in the quarantine rather than deleted. If something you were expecting hasn't arrived, look there first. Open Incoming › Spam quarantine, select the message and choose:

• Release to deliver it to your mailbox;
• Release & Train to deliver it and tell the filter it got it wrong, so it learns;
• Release and Whitelist to deliver it and always allow that sender in future.

Allow and block lists

You can always allow a sender or domain you trust (for example a supplier whose invoices keep being caught), or always block one that keeps getting through. Use Sender allow list and Sender block list under Incoming - Protection Settings in the spam panel.

Quarantine reports

You can choose to receive a regular email listing what's been held in quarantine, so you can release anything genuine without signing in to the panel. Set this up under Reporting in the spam panel (the protection reports).

If email stops arriving

1. Check the quarantine for the missing message.
2. Check your MX records show the three spam filter servers above, and nothing else.
3. Check the destination route points to the server that holds your mailboxes.
4. Still stuck? Ask our support assistant: it can check your domain's email records for you and pass it to our team if needed.