Is the Microsoft 365 or Gmail junk filter enough for a small business?
Microsoft 365 and Gmail already filter spam, so why does so much junk still reach your inbox? What the built-in filters do well, where they fall short, and what to add.
Optima Mail Guard · 30 September 2026
If you use Microsoft 365, Outlook.com or Gmail, you already have a spam filter. So why does your inbox still fill up with sales pitches and offers every day? The short answer is that the built-in filters are designed to catch a different kind of email.
What the built-in filters do well
- Blocking mass spam sent to thousands of people at once.
- Catching viruses, malware and known scam links.
- Rejecting email that fails technical checks, such as messages pretending to come from a domain they don't belong to.
For these jobs, Microsoft and Google are excellent, and you should keep their protection switched on.
Where they fall short
The email that wastes most small businesses' time isn't mass spam. It is cold outreach: SEO and web design offers, lead-generation pitches, software sellers and "quick question" emails. These are sent from real, properly set-up mailboxes, a few at a time, and they are written to look like genuine enquiries. As far as a general-purpose filter is concerned, they are legitimate email, so they go straight to your inbox.
Built-in filters also have to work for everyone, from families to global companies. They can't be too strict about business email without risking hiding real customer messages, so they err on the side of letting it through.
What about Focused Inbox and Gmail tabs?
Outlook's Focused Inbox and Gmail's Promotions tab sort some newsletters and marketing mail out of the way. They help with bulk marketing from companies you have dealt with, but one-to-one sales pitches usually still land in Focused or Primary, because they look like personal email.
What to add
The answer isn't to replace Microsoft or Google, but to add a filter built for business inboxes on top. Optima Mail Guard works behind the mailbox you already use, alongside the built-in protection, and moves cold sales pitches, SEO spam, scams and phishing into a separate folder as they arrive. Your address, your apps and your settings stay exactly the same, and nothing is ever deleted.
It takes about a minute to connect, and you can try it free with 1,000 email checks.
Only the email that matters reaches your inbox.
Try Optima Mail Guard free with 1,000 email checks. No card needed, and it takes about a minute to connect.