Our school has an alumni department that frequently sends bulk emails to our former pupils. A number of messages to plus.com addresses are being rejected as spam with the error message 552 Spam Message Rejected.
We use SPF, Dmarc, DKIM and adhere to all standard policies/email good practice. The recipients are signed up to our mailing list and do need to receive their emails. Is there anything you can do at your end to help these messages be delivered?
I have a few samples of the rejected emails that I can send on if that would help.
Steven McIntosh IT Manager, Erskine Stewart's Melville Schools