Business Email Filtering and Anti-Spam Service

Email is still the front door for most attacks on UK SMEs, which is why filtering sits at the centre of our managed cybersecurity programme and our wider email security stack. This page explains what the service blocks, how we deploy it, and how it compares to relying on Microsoft 365 defaults alone.

What does an email filtering service include?

A managed email filtering service routes your inbound mail through a dedicated filtering gateway before delivery, applies layered detection, and gives you engineers who own the configuration. You get protection without the day-to-day administration falling on your internal team.

• Proactive protection — continuous monitoring and threat detection that stops malicious mail before it lands in an inbox.
• Expert management — UK-based engineers handle configuration, policy updates and incident response, so your team doesn't have to.
• Regular reporting — monthly reports on filtering volumes, incidents handled and recommended improvements.
• Dedicated support — direct access to your account team for changes, releases and escalations, with critical issues responded to within one hour.

How does email filtering work?

Filtering works by sitting in front of your mail flow as the first MX hop. Every inbound message is scored on sender reputation, content and authentication (SPF, DKIM and DMARC) before it is allowed through, quarantined or rejected. Deployment is a four-step process with zero downtime.

1. Email flow analysis — we map your current routing, measure spam and threat volumes, and review existing rules. 2. Filter deployment — rules for spam, phishing, malware and spoofing are configured for your domain and industry. 3. MX cutover — routing is switched to pass through our filtering platform with no lost mail during the change. 4. Ongoing tuning — we review quarantine reports, adjust sensitivity and whitelist legitimate senders to keep false positives near zero.

Sender authentication is the backbone of accurate filtering. If your records are not configured correctly, spoofed mail slips through — see our guide to DMARC, DKIM and SPF setup for the records that make filtering reliable.

Why do UK SMEs need email filtering?

UK businesses face a constant stream of email-borne attacks, and phishing is the most common entry point. Filtering removes the bulk of that volume before a human ever has to make a judgement call — which is the single highest-leverage email control most SMEs can deploy.

• 43% of UK businesses experienced a cyber breach or attack in the last 12 months (Cyber Security Breaches Survey 2025, DSIT).
• 85% of businesses identifying a breach pointed to phishing as the threat type (Cyber Security Breaches Survey 2025, DSIT).
• £3,550 average cost of the most disruptive breach for UK businesses.
• 19,000 UK businesses hit by ransomware in the past year.

The NCSC ranks phishing among the most damaging threats to UK organisations and recommends layered technical controls, including mail filtering and authentication, in its phishing guidance. Filtering paired with user awareness through phishing protection closes the gap that defaults leave open.

Microsoft 365 filtering vs managed gateway filtering

Microsoft 365 ships with Exchange Online Protection (EOP), a capable baseline — but the default policies are deliberately permissive, and tuning them is a job in itself. A managed gateway adds stricter attachment handling, better quarantine control and an engineer who owns the outcome.

Microsoft documents EOP's baseline scope in its Exchange Online Protection overview. Where you run Microsoft 365, filtering complements Microsoft Defender for Business rather than replacing it.

How quickly is email filtering deployed?

For most Microsoft 365 environments, filtering is live within one to two business days. There is no downtime and no disruption to mail flow — the MX cutover is staged so messages keep flowing throughout. Detection then improves over the first few weeks as we tune against your real traffic.

If you have already had an incident, pair filtering with managed detection and response so a missed message is caught and contained quickly rather than discovered late.

Why choose AMVIA for email filtering?

AMVIA is a security-first managed provider, not a telecoms reseller bolting on a filter. Our engineering and support team operates from Sheffield, understands UK compliance requirements, and runs filtering as part of a single accountable security stack.

• Sheffield-based, UK-focused — engineering and support delivered from the UK.
• Accredited and certified — AMVIA holds Cyber Essentials Plus certification and Microsoft Solutions Partner status.
• 1,200+ UK businesses protected — across legal, finance, healthcare and professional services.
• Fast, responsive support — critical issues responded to within one hour, by phone, email and portal, with dedicated account managers.