How to Block Spam and Unwanted Senders in Outlook

Every morning brings the same ritual for a lot of employees in Quebec businesses: open Outlook and sort through a dozen messages that have no business being in the inbox. Dubious promotions, fake invoices, newsletters nobody signed up for. Spam eats time, and more importantly it is often the way in for phishing and ransomware.

The good news is that Outlook gives you several tools to take back control of your mailbox. In this guide we show you how to block spam and unwanted senders, on the desktop app as well as on the web and mobile, then when it makes sense to move to managed protection for your company.

1. Why spam costs your business real money

Spam is not just a nuisance. It is a genuine risk to your company’s security. The vast majority of cyberattacks aimed at small businesses start with an email: a fake delivery notice, a fake payment request, a link that leads to a booby-trapped page. One click from a rushed employee can be enough to compromise an entire network.

Beyond the danger there is the hidden cost of lost time. If every member of your team spends ten minutes a day sorting junk, that adds up to hours of productivity gone every week. For a business in Trois-Rivières or the Mauricie running with a small team, that is far from trivial.

• Risk of phishing and stolen credentials
• Daily time lost across the whole team
• A cluttered inbox where real messages get buried
• A frequent entry point for ransomware

2. Blocking a specific sender in Outlook

The fastest way to stop spam from a known source is to block the sender directly. In the Outlook app on Windows, it takes a few seconds.

1. Right-click the unwanted message in your message list.
2. In the menu, hover over Junk.
3. Click Block Sender.

The message moves straight to the Junk Email folder, and everything that address sends in future will land there automatically. You can review and manage your blocked senders list at any time in the junk email settings, which is handy if you block an address by mistake and want to remove it.

3. Setting the junk email filtering level

Outlook lets you adjust how aggressive its filter is. Depending on how much spam you receive, you can choose a stricter or a looser setting.

Open the Home tab, click Junk, then Junk E-mail Options. You will find several protection levels, from the most permissive to the most restrictive. A high setting catches more spam, but keep an eye on your junk folder for the first few days, because real messages can end up there by mistake.

• No automatic filtering: only blocked senders are set aside.
• Low: catches the most obvious spam.
• High: strict filtering, worth watching closely.
• Safe lists only: only your trusted contacts reach the inbox.

For companies that want a structured approach to email security, our managed IT services include advanced filtering well beyond what Outlook offers out of the box.

4. Blocking an entire domain

Sometimes the problem is not one address but a whole domain. If you get spam from several addresses ending in the same domain name, you can block that domain outright instead of picking off addresses one by one.

In Junk E-mail Options, go to the Blocked Senders tab, click Add, then enter the full domain. Every message from that domain will be treated as junk from then on. It works very well against spam waves that keep changing addresses while keeping the same sending domain.

• Useful against bulk mailing from a single service.
• Avoids blocking dozens of individual addresses.
• Use it carefully so you do not block a legitimate partner.

5. Blocking spam in Outlook on the web and mobile

Do you work mostly in the browser or on your phone? The same tools are there, just laid out a bit differently.

In Outlook on the web

Open the message, click the three dots at the top right of it, choose Block, then confirm. The message moves and the sender joins your block list. You can manage that list in the settings, under Mail then Junk email.

In the mobile app

In the Outlook app on iOS or Android, open the message, tap the three dots, then select the option to move it to junk or report it. Reporting also helps Microsoft improve its filters for everyone.

6. When blocking by hand is no longer enough

Blocking spam manually works fine for personal use. For a business it is an endless fight: spammers rotate addresses, forge legitimate senders and disguise their attacks as credible internal messages. At that point, Outlook’s built-in filter reaches its limits fast.

Managed protection works upstream, before the message ever touches the inbox. It analyzes links, verifies the sender’s authenticity, quarantines suspicious attachments and applies security rules across the whole organization. That is the kind of protection businesses in Trois-Rivières and the Mauricie adopt so they can sleep at night.

• Advanced filtering before the message is delivered.
• Protection against impersonation and targeted phishing.
• Uniform rules for every employee, with no individual setup.
• Continuous monitoring and tuning by specialists.

Frequently asked questions

How do I unblock a sender I blocked by mistake in Outlook?

Go to Junk E-mail Options, open the Blocked Senders tab, select the address in question and click Remove. The sender will be able to write to you normally again.

Does blocking a sender actually delete their messages?

Not quite. The messages do not disappear: they are redirected to your Junk Email folder instead of the inbox. You can empty that folder regularly or set it to empty itself.

Why do I still get spam even after blocking?

Because spammers constantly change addresses and domains. Manual blocking cannot keep up with that pace. A managed email security solution filters threats by their behaviour rather than only by their address, which holds up far better over time.

Protect your business email in the Mauricie

Blocking spam in Outlook is a good first reflex, but only a complete security strategy keeps your mailbox clean for good. Our team works with companies in Trois-Rivières and throughout the Mauricie to put solid email protection in place, sized to their needs. Take a look at our IT services for businesses or write to us through our contact page to talk about what you need.