Email Notifications: Email Notifications: trigger rspamd symbol for bad HELO
Registration email from redmine.org triggers the following rspamd symbol:
From the headers:
Received: from static.184.108.40.206.clients.your-server.de ([220.127.116.11]:43352 helo=Ubuntu-2004-focal-64-minimal)
I think this HELO Ubuntu-2004-focal-64-minimal is what rspamd takes offense at. It should probably be a FQDN.
But TBH I was not able to figure out what exactly the rspamd symbol meant quickly so this might be wrong.
See https://www.rfc-editor.org/rfc/rfc5321.html#section-18.104.22.168 which says
These commands are used to identify the SMTP client to the SMTP server. The argument clause contains the fully-qualified domain name of the SMTP client, if one is available. In situations in which the SMTP client system does not have a meaningful domain name (e.g., when its address is dynamically allocated and no reverse mapping record is available), the client SHOULD send an address literal (see Section 4.1.3).