[exim] Relayed Message: problems sending to list

This is a forward from:

Laura Williamson <laurawilliamson487@???>

    Delivery incomplete

There was a temporary problem while delivering your message to
*exim-users@???*. Gmail will retry for 47 more hours. You'll be
notified if the delivery fails permanently. The response was:

*The MX host does not match any MX allowed by the STS policy. *

I cannot write to the mailing list for the above reason, tried twice :-)

Best