Unable to deliver mail to bigpond email addresses - Mosaico Flexmailer CiviMail - suspected spam IB 703 being reported by Telstra
Yesterday we used Flexmailer and Mosaico for the first time to send a bulk email newsletter (450 emails) through CiviCrm. The email had links, images and text.
We have been using Flexmailer previously with traditional email template last week and did not have a problem. I am suspecting the combination of Mosaico, Flexmailer and Civi.
We are on Wordpress v5.5 and CiviCRM v5.28.3 This (n-1) version of CiviCrm has been running for a couple of weeks without any issues.
We received bounced messages from all bigpond email addresses only.
The message is as follows:-
The response from the remote server was: 558 5.7.1 5ED4071B1EC49D20 Message content rejected due to suspected spam. IB703
The sending server was 134.209.3.79
The sending server is not blacklisted (as per Spamhaus) and there are no shortened URL links in the email.
Our server sends these through a Google SMTP gateway.
We have SPF, DKIM and Dmarc records all set in our DNS. Inspection of the headers shows a pass for SPF and DKIM Verp enabled or disabled has been tried but no change as we still get a bounce from Telstra.
We do not have an issue with any other receiving email servers except Telstra mail servers to email addresses that are bigpond.com, bigpond.net.au
Is there a setting that has to set for bigpond email address so that Telstra mail servers let these pass thru to the recipient?
Could anyone pls let me know if you have seen this problem with bigpond email addresses and how did you resolve the problem.
thanks
mark