10 Office 365 Anti-Spam Policy Best Practices

Spam emails are a major nuisance for businesses, and they can also be a security risk. To protect your organization from malicious emails, it’s important to have an effective anti-spam policy in place.

Office 365 provides a range of anti-spam features, but it’s important to understand how to use them effectively. In this article, we’ll discuss 10 best practices for creating an effective anti-spam policy in Office 365. We’ll cover topics such as setting up filters, configuring rules, and using third-party tools.

1. Use the default anti-spam policy

The default policy is designed to protect your organization from the most common types of spam, such as phishing emails and malicious attachments. It also includes settings that are tailored for Office 365 users, so you don’t have to worry about configuring it yourself.

The default anti-spam policy should be used as a starting point, but you can customize it to meet your specific needs. For example, you may want to add additional rules or modify existing ones to better suit your organization’s requirements. You can also use the built-in reporting tools to monitor how effective the policy is at blocking unwanted messages.

2. Create a custom anti-spam policy for specific users or groups

By creating a custom policy, you can tailor the anti-spam settings to fit the needs of each user or group. For example, if you have a group of users who receive a lot of emails from external sources, you can create a policy that is more restrictive for them than it would be for other users. This way, they will be better protected against spam and malicious emails.

You can also use custom policies to ensure that certain types of emails are always allowed through, such as those from trusted partners or customers. This helps reduce false positives and ensures that important emails don’t get blocked by mistake.

3. Set up an IP allow list to bypass spam filtering for trusted senders

An IP allow list is a list of trusted IP addresses that are allowed to bypass spam filtering. This means that emails from these senders will not be subject to the same level of scrutiny as other emails, and they will have a higher chance of being delivered to your inbox.

This is especially important for businesses who receive emails from customers or partners on a regular basis. By setting up an IP allow list, you can ensure that their emails get through without any issues. Additionally, it helps protect against malicious actors who may try to spoof legitimate email addresses in order to deliver malicious content.

4. Configure connection filtering and content filtering rules

Connection filtering rules help to identify and block malicious IP addresses, while content filtering rules can be used to detect and block suspicious emails. Both of these measures are essential for keeping your Office 365 environment safe from spam and other malicious activity.

Additionally, you should also configure anti-spam policies that allow you to customize the types of messages that are blocked or allowed in your organization. This will ensure that only legitimate emails make it through to your users’ inboxes.

5. Enable safe attachments

Safe attachments allow Office 365 to scan incoming emails for malicious content, such as viruses and malware. This helps protect your organization from potential security threats that could be hidden in email attachments. It also prevents users from accidentally downloading dangerous files.

To enable safe attachments, you’ll need to configure the Exchange Online Protection (EOP) service. You can do this by logging into the Microsoft 365 admin center and navigating to the Security & Compliance section. From there, select Threat Management > Policy > Anti-Spam. Then, click on the Safe Attachments tab and make sure it’s enabled.

6. Block messages with external images

External images can be used to track when a user opens an email, and this information can then be used by malicious actors for phishing or other nefarious purposes.

By blocking messages with external images, you are preventing users from inadvertently giving away their personal information. Additionally, it helps protect your organization’s data from being exposed to potential attackers.

To block messages with external images in Office 365, go to the Exchange Admin Center > Protection > Spam Filter > Edit Settings > Advanced Options > Block Messages With External Images. Check the box next to “Block messages with external images” and click Save.

7. Add additional domains to your block list

By adding additional domains to your block list, you can reduce the amount of spam that reaches your users’ inboxes. This is because spammers often use multiple domains in order to bypass traditional anti-spam filters. By blocking these domains, you can ensure that only legitimate emails are reaching your users.

Additionally, by adding additional domains to your block list, you can also help protect your organization from phishing attacks. Phishers often use spoofed domains in order to make their messages appear more legitimate. By blocking these domains, you can prevent your users from falling victim to a phishing attack.

8. Don’t use wildcards in your block lists

Wildcards are a powerful tool that can be used to block entire domains or subdomains, but they can also lead to false positives.

For example, if you use a wildcard to block all emails from *.example.com, then any email sent from an address like [email protected] will be blocked even though it is legitimate. This could result in important emails being missed and customers not receiving the help they need.

Instead of using wildcards, create specific rules for each domain or subdomain you want to block. This way, you can ensure only the emails you don’t want are blocked while still allowing legitimate emails through.

9. Review quarantine reports regularly

Quarantine reports provide a detailed overview of all the emails that have been blocked by Office 365’s anti-spam filters. This allows you to identify any false positives, i.e., legitimate emails that were mistakenly flagged as spam and blocked from reaching their intended recipients.

By regularly reviewing quarantine reports, you can ensure that no important emails are being blocked due to overly aggressive filtering settings. You can also use this information to fine-tune your anti-spam policy and make sure it is properly configured for maximum effectiveness.

10. Test your configuration changes before deploying them to production

When you make changes to your anti-spam policy, it’s important to test them in a non-production environment first. This will allow you to see how the changes affect your email flow and ensure that they don’t cause any unexpected issues. It also gives you an opportunity to fine-tune the settings before deploying them to production.

Testing your configuration changes is especially important if you’re making changes to the spam filter rules or adding new ones. If these changes are not tested properly, they could lead to false positives (legitimate emails being marked as spam) or false negatives (spam emails slipping through). Testing your changes beforehand can help you avoid these problems.