开云体育

As Bruce said, it apparently means that the member's email service does not recognize Groups.io as a legit email list service, and is applying a limit to the number of messages it will accept from Groups.io's server.

The message doesn't specify whether that limit is being applied per user, or to their service overall. But either way, the member should copy/paste that response code and text to their email service's tech support and explain to them that messages from that server (and Groups.io generally) are wanted and are not to be rejected.

If the member can't get their service to "play nice" perhaps Mark can talk to them. So I'd escalate the issue to him if the email service ignores their customer.

Shal