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 cyber criminals 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 small and medium sized businesses.
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 defence.
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.
And it’s a vital part of your overall cyber security strategy. In fact, it’s right up there with security software, secure backups, and staff awareness training.
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 cyber attacks.
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.
You don’t need to memorise these terms, but it helps to recognise them when you see them in your email system.
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.
All these layers work together to give your business the best possible defence.
Spam filtering isn’t just for big companies. Even a one-person business can (and should) use it. The tools are affordable, often built into the services you already pay for, and can be managed easily by your IT support partner.
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 or 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 rubbish 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 recognise patterns of behaviour.
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 cyber criminals 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 recognise 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 customise 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.
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 cyber criminal 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.
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.
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 cyber security maintenance.
Make staff part of the system
Your people are your first and last line of defence. 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.
Cyber criminals 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 defence.
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 defence)
Let’s be honest, most cyber attacks 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.”
The “Stop and think” checklist
Encourage everyone in your business to follow this simple three-step process when they get a suspicious email:
Stop. Don’t rush. Take a breath before reacting.
Think. Does it make sense? Would that person normally send this?
Check. If it’s from a colleague or supplier, call or message them another way to confirm.
This small habit can prevent major problems.
Make reporting easy
If someone spots a suspicious-looking email, they should know exactly what to do.
Many spam filters and email platforms have a “Report phishing” button. Enable it and show everyone where it is.
If yours doesn’t, create a simple rule like: “Forward suspicious emails to IT@yourcompany.com and don’t click anything.”
The quicker those emails are reported, the faster your IT support partner can block similar ones for everyone else.
Regular reminders keep awareness fresh
Cyber threats evolve constantly, so training shouldn’t be a one-off event.
A few short reminders each month, like a quick email tip or a 5-minute team chat, help keep security front of mind.
You can even run phishing simulations, where fake scam emails are sent to test how your staff respond.
These are great learning tools and help everyone see just how realistic these scams can look.
Celebrate awareness, don’t punish mistakes
If someone falls for a fake phishing test or reports something late, don’t make them feel bad. Turn it into a learning opportunity.
You want people to feel comfortable speaking up. Not worried about getting in trouble. A “no blame” culture encourages everyone to stay alert and proactive.
Spam filtering, security software, and secure backups are all vital. But without informed, cautious people using them, your security chain still has a weak link.
How to keep your filter working at its best
Just like your car, spam filtering runs best when it’s checked and maintained regularly.
Keep everything updated
Spam filters rely on the latest threat intelligence. Information about new scams, fake domains, and dangerous attachments.
The good news is that updates usually happen automatically, as long as they’re turned on. Check with your IT support partner to make sure your system is receiving real-time updates from its security network.
If it’s not, your filter could be missing the latest tricks criminals are using.
Review your quarantine regularly
Every good spam filter has a quarantine area. It’s important to check this area regularly to make sure nothing legitimate has been caught by mistake.
These “false positives” can happen, especially when filters are set to be extra cautious.
Over time, reviewing what ends up in quarantine helps fine-tune your settings for even better accuracy.
Monitor reports and trends
Most spam filtering systems can generate simple reports showing what’s being blocked, where it’s coming from, and how many threats were stopped.
You don’t need to get into the technical detail. Reviewing these reports occasionally gives you a sense of how well your protection is working.
If you notice a sudden spike in phishing attempts, it’s a sign your filters (and your staff training) are being put to the test. It might be worth tightening your settings a little.
Update your allow and block lists
Businesses change all the time. New suppliers, new partners, new clients.
It’s worth reviewing your whitelists and blacklists every few months to make sure they’re still accurate.
If a supplier changes their domain, their emails might suddenly be caught in spam. Or if an old contact starts sending suspicious links, you’ll want to block them fast.
Keeping these lists current avoids frustration and maintains strong protection.
Revisit your filtering rules
When you first set up your spam filtering, you might have created custom rules. Things like blocking certain file types or scanning for keywords.
Over time, it’s useful to revisit those rules with your IT support partner. Are they still relevant? Could they be improved based on what you’ve learned about your email habits?
A quick quarterly review keeps everything aligned with how your business operates.
Test it occasionally
You can (and should) test that your filters are working.
Many security companies offer free test emails that mimic spam or phishing messages. These are safe versions that let you confirm your filter is catching what it should.
Running a quick test now and again ensures nothing’s slipped through the cracks.
Keep your staff in the loop
If your spam filter settings change, for example, if you make the rules stricter or adjust the quarantine notifications, let your team know.
It helps avoid confusion (“Why didn’t I get that email?”) and keeps everyone engaged with your security efforts.
Your people are more likely to take cyber security seriously when they understand what’s happening behind the scenes.
Involve your IT support partner
Most of this maintenance can be handled by your IT support partner. They can:
- Monitor your filtering reports.
- Handle updates automatically.
- Fine-tune your system over time.
That’s one of the big benefits of working with an IT support partner. They quietly take care of these things so you can focus on running your business.
The goal is consistency, not complexity. You don’t need to overhaul your spam filtering every month. A little regular maintenance keeps your protection strong and reliable.
The payoff?
Peace of mind. A safer inbox. And fewer nasty surprises.
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.