Every setup follows the same pattern: prepare your mail platform to accept mail from the filtering service, change your MX records, verify a real message, then lock down direct delivery. The details differ by platform, so each page below covers the exact settings, the checks and the rollback order.
Choose your platform
Microsoft 365 (Exchange Online)
An inbound Partner connector restricted to the filtering service, Enhanced Filtering for Connectors so Microsoft still sees the original sender, and a lockdown that stops attackers delivering straight to your tenant. Weighing whether you need a gateway at all? Read Microsoft 365 built-in filtering vs a gateway.
Google Workspace (Gmail)
The Gmail inbound gateway setting with the filtering service's IP addresses, external IP detection, and the option to reject mail that skips the gateway. Compare first with Google Workspace's built-in protection.
cPanel and WHM
An MX change, email routing set so the server still delivers locally, trusted gateway IPs and SpamAssassin tuning, for hosted servers running Exim. Hosts offering this to customers can read about partnering with us.
Exchange Server (on-premises)
A Receive connector scoped to the filtering service, port 25 locked to the filter, then the MX change. Covers Exchange Server 2016, 2019 and Subscription Edition.
What's the same on every platform
| Item | Included per domain |
|---|---|
| Mailboxes | Unlimited (mailbox count, not message volume) |
| Inbound messages | 100,000 per month |
| Maximum inbound message size | 400 MB (your platform's own limit also applies) |
| Outage spooling | Up to 5 days if your mail server is down |
| Message history | 30 days |
Every user gets a personal quarantine with scheduled digests, and admins get a shared domain quarantine. See all features and pricing.
Before you change anything
- Run the free Email Health Check to see your current MX, SPF and DMARC records.
- Lower your MX record's TTL a day ahead, so the change and any rollback take effect faster.
- If you're replacing another filter, follow how to switch filters without losing email.
Stuck on a step? Our support page lists what to send so we can trace a message quickly.
Frequently asked questions
Do I have to move my mailboxes to use iBlockSpam?
No. Your mailboxes stay where they are. You point your domain's MX records at our filtering servers, and clean mail is delivered on to Microsoft 365, Google Workspace, your cPanel server, Exchange or another standards-based mail server. Users keep the same mail apps and sign-ins.
Which platform steps are needed besides the MX change?
Each platform needs to accept mail from the filtering service and treat it correctly. Microsoft 365 uses an inbound Partner connector with Enhanced Filtering for Connectors. Google Workspace uses the inbound gateway setting. cPanel/WHM needs the right email routing, and Exchange Server a scoped Receive connector.
Can I undo the setup?
Yes. The setup wizard records your current DNS and gives you rollback steps. Rolling back means restoring your previous MX records and reversing any platform restriction that only accepts mail from the filter, in the order each platform page describes.
Related guides
How to use an external spam filter with Microsoft 365 and Enhanced Filtering for Connectors
How to run an MX-level spam filter in front of Exchange Online: Partner connector, Enhanced Filtering for Connectors, why not SCL -1, headers and rollback.
10 min read Setup guidesHow to set up a Google Workspace inbound gateway for a spam filter
Configure Gmail's Inbound gateway for an MX-level spam filter: gateway IPs, external IP detection, direct-mail rejection, TLS, DMARC and rollback.
9 min read Setup guidesHow to put an external spam filter in front of cPanel/WHM
Put an external MX-level spam filter in front of cPanel/WHM: Email Routing, trusted SMTP IPs, blocking direct-to-server spam and SpamAssassin tuning.
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