The Email Security Gap Most MSPs Are Leaving Open
Think through your current client roster. How many of them have a mail server or managed email service? Almost all of them. Now ask: how many have dedicated, managed spam filtering in place — not just whatever basic filtering ships with their hosting plan, but real, configurable, monitored filtering with a spam threshold they've agreed to and logs you can review when something goes wrong?
For most MSPs, the honest answer is: very few. Email security tends to fall into a grey zone. It's not glamorous like endpoint detection, it doesn't generate urgent support tickets the way network outages do, and clients rarely ask for it by name. So it doesn't get prioritized, and it doesn't get sold.
That's a mistake — and not just a revenue mistake. Unmanaged email filtering is a liability. When a phishing email gets through and a client clicks the wrong link, the call comes to you. When a CEO gets hit with a business email compromise scam that a properly tuned spam filter would have flagged, the questions start. You're accountable for the client's IT environment. Email filtering should be part of that environment.
Why Proxy-Based Filtering Is Ideal for Multi-Client MSPs
The fundamental MSP challenge with any add-on service is management overhead. A service that requires per-client installation, on-site configuration, or heavyweight client-side software doesn't scale — you end up spending more on support labor than you earn from the subscription.
Proxy-based spam filtering sidesteps this entirely. The client changes their domain's MX record to point to the filtering proxy. That's it. No software installs on mail servers, no client-side agents, no changes to user workstations. From the client's perspective, mail still arrives in their inbox. From your perspective, you've added a managed, configurable security layer that you control centrally.
With Indition Spam Killer, each domain gets its own configuration. You can manage 50 client domains from a single account. Each domain's settings — spam threshold, custom rules, blocked senders, quarantine behavior — are independent. Changing one client's configuration doesn't touch any other. And the per-domain statistics dashboard gives you visibility into what's happening across all your clients without requiring you to log into each client's environment separately.
The Pricing Opportunity: What Clients Pay vs What You Pay
Email security services typically retail in the $3–8 per mailbox per month range when sold by large security vendors. At that price point, a client with 25 mailboxes is paying $75–200/month for filtering — and if you're the MSP managing that relationship, that revenue should be yours.
With a proxy-based approach priced per domain rather than per mailbox, the math gets even more interesting. A client with 50 mailboxes across a single domain pays one domain price, not fifty per-seat fees. For clients with large teams or heavy email volume, per-domain pricing is dramatically cheaper than per-seat alternatives — which makes it easy to present as a cost-effective option while still building in healthy margin.
Consider a typical MSP scenario: you're managing 30 clients, each with one to three domains. At a comfortable per-domain markup, you're looking at meaningful monthly recurring revenue added to your book of business with near-zero incremental support burden. The service runs itself once configured. Support tickets are rare because the filter works silently in the background. When something does come up — a false positive, a blocked legitimate sender — the fix is a configuration change you can make in under two minutes from the admin dashboard.
How to Pitch Email Filtering to Existing Clients
The ROI angle is straightforward: a single phishing incident that leads to a credential compromise, ransomware deployment, or wire fraud attempt will cost your client far more than a year of spam filtering fees. You don't need to be alarmist about it — the numbers speak plainly. The FBI's Internet Crime Complaint Center reports that business email compromise losses run into the billions annually, and the average small business incident runs tens of thousands of dollars including downtime, forensics, and remediation.
Frame the conversation around three points:
- Cost of a single incident. One successful phishing attack likely costs more than several years of filtering. Spam filtering is cheap insurance against expensive events.
- Compliance posture. Industries with data handling requirements — healthcare, finance, legal, insurance — often have obligations around protecting client communications. A documented, managed filtering layer with audit logs strengthens their compliance position.
- Productivity. Spam isn't just a security risk; it's a productivity tax. Employees who spend 10 minutes a day sorting spam are losing meaningful work hours annually. Better filtering pays for itself in reclaimed attention, even setting aside security considerations entirely.
Most clients, when the conversation is framed this way, say yes without needing much more convincing. They assumed you were already handling it, or they've been vaguely aware it was a gap and just needed someone to close it.
Why Support Burden Stays Low
Spam filtering done right is an invisible service. When it's working, users don't notice it — they just notice that their inbox is cleaner. Support tickets come from two scenarios: false positives (legitimate mail getting blocked) and false negatives (spam getting through).
False positives are rare with a well-tuned default configuration, and when they do occur, the fix is adding an allowlist entry for the blocked sender — a 30-second task. False negatives prompt users to ask why a particular spam message got through, which is a good opportunity to refine the spam threshold or add a custom rule for the pattern.
Centralized per-domain dashboards mean you can investigate either type of issue without involving the client's IT contact or visiting their environment. Pull up the domain, search the logs for the message in question, and you have the full picture: what score it received, which rules triggered, what the disposition was.
That's the support model MSPs need: fast diagnosis, simple fixes, no site visits. Email filtering through a proxy fits that model naturally. It's the kind of service that generates a thank-you email rather than a support ticket — and that's exactly what recurring revenue looks like when it's working as intended.