Check for Blacklisted Email
We have a customer that we invoice on a regular basis and just today invoices have randomly rejected.
Sorry, email delivery was unsuccessful.
Subject: Invoice
Destination: customer email redacted
Sent: December 8th 2023, 3:14:43 pm
Diagnostic-Code: rejected
That's literally as much information as we get. I have reached out to the customer, they say nothing has changed. We are a small team and don't have an IT department. Have you somehow blacklisted the email? Invoices sent earlier in the week worked just fine.
