You know that feeling when you open your inbox in the morning, and it’s already full of junk?
Special offers you never signed up for. “Urgent” invoices from companies you’ve never heard of. Mysterious delivery updates for parcels you didn’t order.
Most people just sigh, delete, and move on.
But what if one of those emails wasn’t just annoying? What if it was dangerous?
That’s what spam is today.
It’s one of the most common ways cybercriminals break into businesses like yours.
Spam isn’t what it used to be
Once upon a time, spam was just an inconvenience. You’d get odd emails about winning the lottery or inheriting money from a long-lost prince.
Now it’s much more sophisticated.
It might look like an invoice from a supplier you use, or a message from a delivery company. It might even appear to come from one of your team.
Behind those emails are criminals trying to:
- Steal your passwords or bank details
- Infect your computers with malware (malicious software that can take control of your data)
- Trick your staff into transferring money or giving access to your systems
And they don’t need to target you personally. They send out millions of these emails every day, knowing that it only takes one click to cause real damage.
You might think: “Surely hackers go after the big companies?”
They do. But they also love SMBs.
Why?
Because they often have fewer defences in place.
They might not have dedicated IT security teams. They might rely on built-in email protection and assume it’s enough.
That makes them easier to catch off guard.
And the impact can be huge, from losing access to important files to having your reputation damaged with customers.
The good news: You can stop most of it
Spam filtering is your first line of defense.
Think of it as a bouncer for your inbox. It checks every incoming email before it’s allowed in. If something looks suspicious, it gets blocked or quarantined.
A good spam filter can stop more than 99% of dangerous or unwanted emails before they ever reach you. That’s thousands of potential threats gone, automatically.
But it’s not just about blocking junk.
It protects your data, your money, and your staff from the scams that slip through the cracks.
What is spam filtering?
Let’s clear up one thing first: Spam filtering isn’t for cleaning up your inbox because it’s messy.
It’s for protecting your business from one of the biggest sources of cyberattacks.
When you think of your email inbox, imagine it like the front door to your office. You wouldn’t let just anyone walk in off the street, right? You’d want to know who they are and what they want.
A spam filter does exactly that. It stands guard at the door, checking every single email that tries to get in.
First, let’s make sure we’re speaking the same language:
Phishing: Emails pretending to be from someone you trust (like your bank or a supplier), designed to trick you into giving away information.
Malware: Malicious software that can infect your device when you click a link or open an attachment.
Blacklist: A list of known bad senders with email addresses that are automatically blocked.
Whitelist: Approved senders that are always allowed through.
Quarantine: A holding area where suspicious emails wait until someone checks them.
Types of spam filtering
There are a few different levels of filtering that work together…
- Email provider filtering: Most platforms, like Microsoft 365 or Google Workspace, include built-in spam protection. It’s a good start, but not always enough on its own.
- Advanced or third-party filters: these sit in front of your email system and add extra layers of protection. They can catch sophisticated phishing emails or malicious attachments that basic filters might miss.
- Your own rules and settings: You (or your IT support partner) can fine-tune how strict your spam filtering is. You decide what gets quarantined, what gets allowed, and what gets blocked automatically.
Why every business needs spam filtering
You probably rely on email more than almost anything else. It’s how you communicate with customers, suppliers, and your own team.
But here’s the uncomfortable truth: Every time you open your inbox, you’re opening a door to potential threats.
That’s why spam filtering is essential.
It’s easy to roll your eyes at junk mail. But hidden among the obvious nonsense (“Claim your free iPhone!”) are emails that look convincing.
They might copy your supplier’s logo. They might use your accountant’s name. They might even quote a genuine invoice number stolen from a previous data breach.
And all it takes is one click, one quick moment of trust, for things to go badly wrong.
What can happen if you don’t filter spam
Data theft:
A phishing email can trick someone into entering passwords or banking details on a fake website. Once stolen, those details can be used to access your systems or sell your data on the dark web.
Malware and ransomware:
Some spam emails include attachments or links that secretly install malicious software. Ransomware can lock you out of your own data until you pay a ransom.
Lost productivity:
Even if the emails aren’t dangerous, sorting through junk takes time. A few minutes here and there across your whole team soon adds up to hours of wasted time each week.
Reputation damage:
If a customer gets a fake email that looks like it came from you, it can damage trust. Even if it wasn’t your fault.
In short, spam is an open door to financial loss, downtime, and embarrassment.
Spam filtering stops attacks before they start
A good spam filter catches dangerous emails before they reach your people, stopping most attacks before they can begin.
Instead of relying on every employee to spot every scam, you build a protective wall around your inbox.
That single step can prevent most email-based threats from ever touching your business.
It also keeps your team focused. When your inboxes aren’t cluttered with junk, your team spend less time deleting garbage and more time doing productive work.
How spam filters work
Spam filtering is made up of layers. A series of security gates that every email must pass through before it’s allowed anywhere near you or your team.
Reputation checks: Who’s sending the email?
The first thing a spam filter looks at is where the email came from.
Every email comes with digital fingerprints. Technical details that show which server sent it, and whether that server has a good reputation or a bad one.
If the sender’s address or domain is known for sending spam, it’s immediately blocked. If it’s a trusted source, the email moves to the next stage. If it’s somewhere in between, it might be quarantined for review.
Content scanning: What does the email say?
Once the sender checks out, the filter looks inside the email itself. It scans:
- The subject line for spammy language (“urgent action required”, “click here”, etc.)
- The message body for suspicious patterns (poor grammar, strange links, or odd formatting)
- Any attachments for hidden malware
These checks happen in milliseconds. The filter compares the email against thousands of rules and patterns built from previous attacks.
AI and machine learning: Getting smarter every day
Older spam filters worked like a list of rules. If an email contained certain words or came from certain addresses, it was flagged.
Modern filters go far beyond that. They use AI (artificial intelligence) and machine learning to recognize patterns of behavior.
For example, if scammers start using a new type of phishing email worldwide, the AI can spot the trend and automatically learn to block similar emails. Even before a human updates the system.
In short, the more spam the filter sees, the smarter it gets.
Link and attachment analysis
Links are one of the most common ways cybercriminals trick people.
Spam filters don’t just look at what the link says. They check where it leads. If it redirects to a suspicious website or one known for hosting malware, the email is blocked or quarantined.
Attachments get similar treatment. They’re scanned for dangerous code, fake document macros, and anything that looks like ransomware.
That means even if an email looks harmless, its contents are being checked in the background for hidden threats.
User feedback: Learning from real people
Modern spam filtering systems also learn from you and your team.
When you click “mark as spam” or “not spam,” you’re training the system. It records what you trust and what you don’t, improving accuracy over time.
That feedback is shared across millions of users worldwide, helping filters recognize new scams faster.
This is why it’s important that you don’t simply delete spam emails, but flag them as spam first.
Quarantine and reporting
If an email looks suspicious but not 100% certain to be bad, it’s sent to a quarantine area.
From there, you or your IT support partner can safely review it without opening the email itself.
This extra step prevents false positives (good emails accidentally marked as spam) while keeping risky messages isolated from your main inbox.
Continuous updates
Scammers don’t stand still. But neither do spam filters.
The best systems update constantly, pulling in new threat data every few minutes.
That way, when a brand-new phishing campaign starts circulating, your filter already knows how to stop it.
All these layers add up to powerful protection
Each layer might miss something on its own, but together, they form a strong defence.
- Reputation checks stop known spammers
- Content analysis spots suspicious messages
- AI and human feedback catch new, evolving threats
The right way to set up spam filtering
Spam filtering doesn’t have to be complicated. In fact, most of the hard work happens automatically… once it’s set up correctly.
Start with what you already have
If your business uses Microsoft 365 or Google Workspace, you already have a basic spam filter built in.
Systems like these do a decent job by default, but the settings are often left on “standard” which might not be enough for your business.
Your IT support partner can adjust those settings to make them more effective, such as:
- Increasing the sensitivity level to catch more suspicious emails
- Automatically quarantining high-risk messages instead of delivering them
- Blocking known malicious domains or senders
- Enabling real-time link and attachment scanning
It’s a simple but powerful first step.
Add an extra layer for better protection
Think of built-in spam filtering as a lock on your front door. It’s important, but you might still want an alarm system too.
Third-party spam filtering tools add that extra layer.
They sit between the internet and your email platform, catching harmful emails before they even reach Microsoft 365 or Gmail.
Your IT support partner can help you choose and configure one that fits your size and budget.
These tools offer:
- Advanced phishing detection (to catch fake “urgent payment” or “invoice” emails)
- Attachment sandboxing (testing attachments safely before you open them)
- Detailed reports and analytics (so you can see what’s being blocked)
You don’t have to understand the technical details, just know that this extra layer dramatically reduces your risk.
Create your own rules and safe lists
Once the main filtering is in place, you can customize it for your business. For example:
- Add trusted senders to a whitelist (so important emails don’t get stuck in quarantine).
- Add known spammers or scammers to a blacklist.
- Set up rules to block emails containing certain words, phrases, or attachment types.
These tweaks make your filter more personal and more accurate over time.
Review your quarantine regularly
Even the best filters aren’t perfect. Sometimes legitimate emails end up quarantined by mistake. These are known as false positives.
Make it part of your routine (or your IT support partner’s routine) to check the quarantine area daily or weekly. That way, you don’t miss anything important, and you can fine-tune your settings to prevent repeat issues.
Don’t forget outbound protection
Spam filtering doesn’t only look at incoming emails. Good systems also check outgoing messages to make sure your own accounts aren’t sending spam. For example, if a cybercriminal gets hold of one of your email accounts.
This protects your domain reputation (so your legitimate emails don’t end up in other people’s spam folders) and alerts you quickly if something suspicious is happening.
Keep it up to date
Spam filters rely on constant updates to stay effective.
New scams appear every day, and the filters learn from global data to stay one step ahead.
Make sure automatic updates are turned on, and schedule regular reviews of your email security settings. Ideally every few months. Your IT support partner can help with this as part of your overall cybersecurity maintenance.
Make staff part of the system
Your people are your first and last line of defense. Encourage them to:
- Report suspicious emails instead of just deleting them
- Avoid clicking links in emails they weren’t expecting
- Never open attachments unless they’re 100% sure they’re legitimate
Many spam filters include a “Report Phishing” button that sends examples straight to IT. Make sure your staff know how to use it.
Test and adjust
Every business is different. What works perfectly for one might be too strict or too relaxed for another.
Do a short test period when you first tighten your filters.
Monitor what’s getting blocked and tweak the rules until you’ve struck the right balance between safety and convenience.
Good setup = quiet inbox, safer business
When spam filtering is properly configured, it fades quietly into the background, doing its job without interrupting your day.
The difference you’ll notice is what doesn’t happen: Fewer scam emails, fewer wasted minutes deleting junk, and a much lower chance of an expensive mistake.
Training your people is just as important
Even the best spam filter in the world can’t catch everything.
Cybercriminals are constantly changing their tactics, and every so often, a bad email slips through.
That’s why your people, not just your technology, are your greatest line of defense.
If your staff know what to look for and what to do when something seems suspicious, you’ll drastically reduce the chances of a costly mistake.
The weak link (and the strongest defense)
Let’s be honest, most cyberattacks don’t start with a technical failure. They start with a human one.
Someone gets an email that looks urgent. It might say:
“Your account has been suspended. Click here to verify your details.”
In a hurry, they click the link and enter their password. Within minutes, a criminal has access to your email system, client data, or cloud files.
It’s a simple mistake. And it happens every day to businesses just like yours. But with a bit of awareness training, those mistakes become far less likely.
Spotting the red flags
Teach your team to pause and think before they click. Most phishing emails have warning signs if you know what to look for.
Here are a few easy ones to remember:
- Check the sender: Is the email really from who it says it’s from? Look carefully at the address. Scammers often change one letter in a name or domain.
- Look for urgency or fear tactics: “Act now or your account will be closed” is a classic trick.
- Check the links: Hover your mouse over a link before clicking. If it doesn’t go where it claims, don’t touch it.
- Poor spelling or grammar: Professional companies rarely make basic errors.
- Unexpected attachments: If you weren’t expecting a file, don’t open it.
- A good rule of thumb: “When in doubt, don’t click.”
How to keep your filter working at its best
Just like your car, spam filtering
- Keep everything updated
- Update your allow and block lists
- Revisit your filtering rules
- Test it occasionally
- Keep your staff in the loop
- Involve your IT support partner
Don’t wait for a problem to happen. Make sure your spam filtering and wider security setup are up to date now, and you’ll stay one step ahead of the scammers who never stop trying.
Not sure how well your business is protected from spam and phishing?
We can help you find out. Get in touch.
