Emails bouncing back for TPG, Bigpond and iinet Australian email providers

[LeahGustavsson]

Since February we have been experiencing issue with australian email providers including TPG, Bigpond and Iinet where our emails which were previously working and received are now bouncing back due to the following error. 

550 5.7.350 Remote server returned message detected as spam -> 558 5.7.1 Message content rejected due to suspected spam. IB703;i{85c4e49f-baf3-4477-b551-87e68c4381ec}

We are aware of the protocol changes which occurred in February and updated our DKIM, DMARC and SPF polocies to align with the authetication changes.  I have run our emails through the https://www.mail-tester.com/ to test its spam score and there is nothing which indicates that the email should be identified as Spam.  

How can this issue be resolved as this is impacting our two businesses and our customers are becoming very frustrated that our emails are not being received. 

[LeahGustavsson]

Sorry I should mention, we are using Office 365 with email sent from outlook.

[Aubrey]

Hi @LeahGustavsson, who's your email provider? Have you tried sending emails using a web browser? 

[LeahGustavsson]

Hi @Aubrey I am using a Office 365 exchange account with the emails sent using outlook. The emails are sent are from two repuable businesses where the email addresses which were working fine before the changes in February.  

I have tried to email postmaster@tpg.com.au from a wide variety of email addresses and all of them have failed with the same 550 error. 

[BasilDV]

Hi @LeahGustavsson 

So basically, you are not a TPG customer, but a business which sends email to our customers, right?

We'd like to check the address that you are using. Please send it via private message and we'll assess this for you.

BasilDV

[LeahGustavsson]

Hi @BasilDV,

That is correct.  I've sent a private message as requested.  Would you be able to advise why our email domains have only started being rejected as spam in case this is a problem for other companies?

Thanks,
Leah