Hi,
We're an ESP sending emails on behalf of cleints who are receiving the following bounce error from virgin media domains (blueyonder, ntlworld, virginmedia) across multiple different domains and IPs:
SMTP service unavailable: "421 4.2.0 MXIN618 Temporary SMC Policy Violation detected, retry later ;id=KdKFlqEMxa7TsKdKFlL2Ap;sid=KdKFlqEMxa7Ts;mta=mx12.tb;dt=2021-03-12T09:39:16+01:00;ipsrc=xx.xx.xx.xx;" received from mx.tb.ukmail.iss.as9143.net (212.54.56.11) while connected from SENDINGDOMAIN.co.uk (xx.xx.xx.xx) to mx.tb.ukmail.iss.as9143.net (212.54.56.11)
We have tried "sending later", as suggested in the error but no emails are being allowed through. Would someone please be able to help me with the cause of this error, and how we may resolve it moving forwards? I can't find any information on it online nor action I can take for it to be removed.
If there is elsewhere better to post this question, please let me know and I'll be happy to move it.
Many thanks,
Chris