Outlook emails marked as spam by Gmail due to new anti-spam guidelines

Some Outlook.com users are having trouble sending emails to Gmail accounts, with messages being blocked and marked as spam. This issue only affects users with non-standard Outlook.com domains (e.g., @hotmail.fr, @outlook.sk).

Microsoft advises affected users to create an Outlook.com alias (a secondary email address) and use that to contact Gmail users. This is a temporary solution until Microsoft resolves the underlying issue.

The root cause seems to be Google’s recently implemented stricter anti-spam guidelines. These guidelines aim to crack down on spam and phishing attempts by requiring bulk senders to meet specific thresholds and authenticate their messages.

Google began enforcing these guidelines in April 2024 and will fully implement them by June. Non-compliant emails are being blocked or sent to spam folders, as reported here.

If you are experiencing email deliverability issues, a couple of tips might help you solve the problem. For Outlook.com users who are having trouble sending emails to Gmail recipients, creating an Outlook.com alias can be a temporary solution. This will allow you to use a different email address to contact Gmail users.

If you send emails in bulk, you must comply with Google’s Bulk Sender Guidelines to avoid blocking your emails by Gmail. These guidelines include implementing stricter spam thresholds and message authentication to ensure that your emails are not marked as spam.

By following these guidelines, you can improve your email deliverability and avoid blocking your messages.

More here.