Anyone had any issues with sending to Shaw email addresses recently?

I have a client that sends out smallish batches of emails once every week or so, and last week a number of them we blocked, but some went through.

Never had this happen before.

I confirmed with shaw that some of the addresses were active and receiving emails but that's about as helpful as they would allow themselves to be.

Returned email (with email addresses made private):

This is the mail system at host leaf102.mfilter.dimenoc.com.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

                   The mail system

<-shawuser1-@shaw.ca>: host shw-central.mx.a.cloudfilter.net[15.222.199.59]
    refused to talk to me: 554 shw-ibgw-4002a.ext.cloudfilter.net cmsmtp
    72.29.89.5 blocked AUP#BL

<-shawuser2-@shaw.ca>: host shw-central.mx.a.cloudfilter.net[15.222.199.59]
    refused to talk to me: 554 shw-ibgw-4002a.ext.cloudfilter.net cmsmtp
    72.29.89.5 blocked AUP#BL
Reporting-MTA: dns; leaf102.mfilter.dimenoc.com
X-Postfix-Queue-ID: 867B32645F
X-Postfix-Sender: rfc822; sender@company.com
Arrival-Date: Tue, 30 Apr 2024 13:00:50 -0400 (EDT)

Final-Recipient: rfc822; -shawuser1-@shaw.ca
Original-Recipient: rfc822;-shawuser1-@shaw.ca
Action: failed
Status: 4.0.0
Remote-MTA: dns; shw-central.mx.a.cloudfilter.net
Diagnostic-Code: smtp; 554 shw-ibgw-4002a.ext.cloudfilter.net cmsmtp 72.29.89.5
    blocked AUP#BL

Final-Recipient: rfc822; -shawuser2-@shaw.ca
Original-Recipient: rfc822;-shawuser2-@shaw.ca
Action: failed
Status: 4.0.0
Remote-MTA: dns; shw-central.mx.a.cloudfilter.net
Diagnostic-Code: smtp; 554 shw-ibgw-4002a.ext.cloudfilter.net cmsmtp 72.29.89.5
    blocked AUP#BL