I am trying to use a Google Workspace SMTP relay. I followed the docs on setting up a postfix relay host through the UI.
When I trigger the test mail (setting
from as two different addresses on my domain), everything looks good and google does accept my outgoing mail. However, mailcow does not accept the incoming message.
Here are my settings:
- username and password set to a google workspace account
- in google workspace:
- allow all addresses on my domain as sender
- allow my public IP to use the SMTP relay
- require auth
- in my DNS settings:
- TXT record:
"v=spf1 +a +mx include:_spf.google.com ~all"
- also TXT records for DKIM (both mailcows and googles)
- also DMARC record
- if you want to have a look, the domain is
As for the rejected mail:
- google relay seems to accept the mail and sends it to my server
- rspamd reports
- if helpful, I can provide a
.eml file (I think it doesn’t contain any private information anyway)
What I am trying to achieve is to send all my mails through a relay that has good reputation. If someone knows a better relay service than google, feel free to suggest them if it can potentially fix the issue.