Emails Suddenly Landing in Spam/Junk Folders

lumideez

Hi everyone,

I’ve been facing an issue recently with my domain’s email delivery. My emails, which used to work perfectly fine, have now started landing in the spam/junk folder on popular mail clients such as Gmail, Outlook, and Hotmail.

For context:

I use my domain mailbox both for regular communication and for Brevo campaigns.

I had already added Brevo’s DNS information (SPF, DKIM, etc.) to my domain records, and everything was working smoothly before.

The problem only started happening recently, and I can’t pinpoint what might have changed.

Has anyone experienced something similar, or does anyone know possible reasons why this might suddenly start happening? Any troubleshooting advice or fixes would be really helpful.

Thanks in advance!

esackbauer

lumideez The problem only started happening recently, and I can’t pinpoint what might have changed.

Maybe you installed Mailcow release 2025-09 and therefore activated MTA-STS?

lumideez

esackbauer yeah i ran the update. how do i disable it please? many thanks

mlcwuser

lumideez how do i disable it please?

As far as I know, it is not enabled by default. You have to set a policy for each domain in the admin interface, and then set up the correct DNS records for it to become active.

I would recommend doing so because, at least with Google, one of the first email providers that implemented it, it should actually even help to improve deliverability. If nothing else, it will definitely help to improve security: https://support.google.com/a/answer/9261504?hl=en

esackbauer

Either configure it properly (like DNS and SSL certificate for mta-sts.yourdomain.com) or disable it in GUI:
https://docs.mailcow.email/post_installation/setup-mta-sts/

lumideez

esackbauer I just checked my Admin UI ..there’s no MTA-STS settings on the dashboard

Cisco30

you need to edit the domain settings

lumideez

Cisco30 Aha thanks for the screenshot. It was not active but now its active. I just want to stop my mails going to Gmail’s spam/junk folder.

I’ve tried everything.