Short answer: Blocking individual senders in Outlook or Gmail is a short-term fix, because spammers change addresses constantly. The lasting fix is a spam filter that scans mail before it reaches the mailbox; for businesses that is usually a gateway placed in front of the mail server through the MX record. On top of that, publishing a DMARC policy for your own domain stops forged mail sent in your name.
1. Block the sender in Outlook
In classic Outlook for Windows, right-click the message → Junk → Block Sender. In Outlook on the web and the new Outlook, open the message and choose … → Block. In classic Outlook, Junk → Junk E-mail Options also lets you raise the protection level and keep a safe senders list.
Limitation: it blocks one address, for one mailbox. Spammers use new addresses in every campaign, so the effect is small.
2. Block and filter in Gmail
Open the message → ⋮ → Block "[sender]". To catch a recurring pattern (the same phrase in the subject line, for example), use the search options icon in the search bar to create a filter and choose Delete it, or apply a label with Skip the Inbox. Using Report spam also trains Gmail's filter.
3. Unsubscribe from legitimate newsletters
If a company you know sends marketing you no longer want, use its unsubscribe link (Gmail and Yahoo show a one-click Unsubscribe next to the sender for bulk mail). Never click unsubscribe links from senders you do not recognize: it confirms your address is live, brings more spam, and can lead to a phishing page.
4. Keep your addresses out of sight
- Use a contact form on your website instead of plain-text addresses; bots harvest addresses from web pages.
- Separate role addresses such as
info@andsales@from personal ones. - Use a separate address, not your work address, for trade shows, giveaways and forum sign-ups.
5. Turn on server-side filtering
On cPanel hosting, open Email → Spam Filters to enable Apache SpamAssassin and set the score threshold (the default is 5; lower values mark more mail as spam and raise the false positive risk). Plesk has a similar setting under Mail → Spam Filter. This costs nothing, but spam still reaches your server and consumes its resources.
6. Put a spam filter (gateway) in front of your server
For businesses, this is the most effective method. You point your domain's MX record to an email security gateway, and every incoming message goes through blocklists, authentication checks, content analysis and virus scanning before it reaches your server. Suspicious mail waits in quarantine, where each employee can see their own.
- It works centrally for the whole company; nobody has to configure anything on their own device.
- Malicious attachments never reach employees' computers.
- Your server is not kept busy with spam and mailboxes do not fill up with junk.
How it works in detail: what is a spam filter?
7. Set up SPF, DKIM and DMARC for your own domain
Some of the most dangerous spam your staff receive appears to come from your own domain, such as a fake invoice "from accounts@yourcompany.com". With a DMARC policy of p=reject, major providers and filters reject that kind of forgery. Check your records, and if anything is missing follow the setup guide for your platform.
8. Train your staff
No filter catches everything. For the few phishing emails that slip through, employees are the last line of defense. A short, concrete checklist is enough: how to spot a phishing email: 7 warning signs. To see where a suspicious message really came from, paste its headers into the email header analyzer.
Methods compared
| Method | Scope | Effect | Cost |
|---|---|---|---|
| Blocking in Outlook / Gmail | One user, one address | Low | Free |
| Server filter (SpamAssassin) | One server | Medium | Usually included in hosting |
| Gateway spam filter | Whole company, all domains | High | Monthly subscription |
| SPF, DKIM, DMARC | Spoofing of your domain | High against spoofing | Free (DNS records) |
| Staff awareness | The few messages that get through | Complementary | Time |
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Frequently asked questions
I blocked the address but spam keeps coming. Why?
Spammers send the same campaign from hundreds of different addresses, so blocking by address is never a lasting fix. You need a filter that scores content and reputation.
I'm getting spam from my own address. Was my account hacked?
Usually not. Spammers can put any address in the From field, and without DMARC on your domain those messages get through. If you are unsure, change your password anyway and set up DMARC.
Will blocking spam also block important email?
A well-configured filter does not delete suspicious mail; it quarantines it. You can spot an important message in the daily digest, release it with one click and mark the sender as trusted.