Send & Receive Issues

How to Prevent Microsoft 365 Emails from Going to Gmail Spam

Elise Williams Oct 9, 2026 868 views

Question details

The user needs to prevent outgoing emails from their Microsoft 365 custom domain from being marked as spam by Gmail.

How to Prevent Microsoft 365 Emails from Going to Gmail Spam

Product: Microsoft 365
Device & OS: not provided
Scenario: Sending emails from a Microsoft 365 account using a custom domain to Gmail recipients.
Observed behavior: Emails are consistently being delivered to the recipients' Gmail spam or junk folders instead of their primary inbox.

Before you start

Ensure you have administrator access to your domain's DNS settings and your Microsoft 365 admin center before proceeding with authentication changes.

Solution 1Recommended

Configure SPF and DKIM Records for Your Domain

Setting up Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) authenticates your emails, proving to Gmail that they are legitimate.

Missing or incorrect email authentication records are the primary reason legitimate emails are flagged as spam. Properly configuring SPF and DKIM proves to Gmail that Microsoft 365 is authorized to send emails on behalf of your custom domain.

Access Microsoft 365 DNS settings

Sign in to your Microsoft 365 admin center, navigate to 'Settings', and click on 'Domains'. Select your custom domain and review the DNS records section to find your SPF TXT record.

Update the SPF record

Log in to your domain registrar's DNS management console and add or update the TXT record for SPF (usually 'v=spf1 include:spf.protection.outlook.com -all').

Enable DKIM in Defender

In the Microsoft 365 Defender portal, go to 'Policies & rules', select 'Threat policies', and then choose 'Email authentication settings'. Select DKIM and generate the required CNAME records.

Publish DKIM records

Add the newly generated CNAME records to your domain's DNS settings at your registrar, then return to Microsoft 365 to toggle the DKIM signing switch to 'On'.

Configure SPF and DKIM Records for Your Domain

DNS Propagation Delay: DNS changes can take up to 48 hours to fully propagate across the internet. Your emails may still be flagged as spam during this transition period.

Solution 2

Add Sender to Gmail Safe-Sender List

Instruct your Gmail recipients to manually whitelist your email address to bypass local spam filters.

Free Microsoft Office alternative

Try WPS Office for Seamless Document Management

While email deliverability is managed through your domain settings, choosing the right software for your attachments is just as important. WPS Office provides a free, highly compatible alternative to Microsoft Office, letting you create professional documents without the heavy subscription fees.

1. Download the software: Visit the official WPS Office website and download the free installer for your operating system.
2. Install WPS Office: Run the downloaded installation file and follow the simple on-screen instructions to set up the software.
3. Open and edit your files: Launch WPS Office and instantly open your existing Word, Excel, or PowerPoint documents to continue working effortlessly.

Easily create, edit, and save professional documents to attach to your Microsoft 365 emails.Fully compatible with Microsoft Office formats, ensuring your DOCX, XLSX, and PPTX files open perfectly.Free and lightweight suite, requiring minimal system resources and disk space.Familiar user interface that requires zero learning curve when switching from other office suites.

Frequently Asked Questions

Why do Microsoft 365 emails suddenly go to Gmail spam?

Google frequently updates its strict spam filtering policies. If your custom domain lacks proper email authentication like SPF, DKIM, or DMARC, Gmail is highly likely to flag your messages as unverified and automatically route them to the spam folder.

Do I need a DMARC record to prevent email spam issues?

Yes, setting up a DMARC record is highly recommended. Once SPF and DKIM are configured, a DMARC policy instructs receiving servers like Gmail on how to handle emails that fail authentication, significantly improving your sender reputation.

How can I test if my SPF and DKIM records are working?

You can use free online email deliverability tools such as MXToolbox or Mail-Tester. By sending a test email from your Microsoft 365 account to the unique address provided by these tools, you can receive a detailed report on your SPF and DKIM status.

Outlook & Email Problems