Windows 10: Bulk emails with BCC addresses are kicked back as including spam by the Administrator

Recently since I upgraded to Windows 11 any bulk emails sent out to BBC of 25 names are kicked back as deliverable because the email was judged to include spam by the administrator. My email provider is Centurylink.net and I have been in contact with them and am told that the problem isn't on their end, rather the problem is caused by email client Outlook 365. This problem only occurs when I send out bulk and not individual emails. I need to resolve this issue as I'm dead in the water if I don't.

:)

 

Bcc emails rejected as spam

I suspect your IP address has been (maybe only temporarily?) flagged as a source of spam, again by either your or their ISP.

 

Bcc emails rejected as spam

Thanks for the suggestion but I've just tried sending a message to just 4 recipients and 3 were rejected and one went to a spam folder so it isn't the quantity in the bcc field that matters.

 

Bcc emails rejected as spam

Spamhaus, I think that is entirely from intended recepient having signed up for an interceptor service, such captures any/all emails, rejects the ignore listed, forwards secretly the ones not on the ignore list.
Because of the aggressive anti-spam engines out there, I still recommend no more than 20-25 names in the bcc, with yourself in the To field, thus immediately identifying to all who you are.
And, make sure you have a crystal clear brief Specific Purpose Statement in the Subject field. Continue to avoid what I call the [famous MLM] ploy: "I invite you to an exciting fun-filled gathering!"