550 #5.7.1 SPF unauthorized mail is prohibited./

[Postmaster-ON]

Good morning,

I'm hoping to reach the Postmaster in relation to the subject. We are a mid-size ESP and one of our clients is experiencing the subject-referenced error. Can you please provide a contact or direction so that I may provide headers to resolve this issue.

Thank you!

[BasilDV]

Hi @Postmaster-ON 

Have you checked your SPF records if it's updated?

Kindly send us a PM with the email address and the complete header for further checking.

BasilDV

[Postmaster-ON]

Hi @BasilDV,

Any news from the Postmasters regarding my PM?

[BasilDV]

Hi @Postmaster-ON 

We did not receive any private message with the requested details/information.

Kindly send it again directly to me.

BasilDV