I think the claim here is that Atlassian's post-sales account representatives ("customer success"?) would have proactively reached out to the technical contacts of large companies with a personal email - and known exactly what person to talk to, because they stay in touch - because Atlassian is an organization like Amazon, Microsoft, or Salesforce.

I think you're reading it as saying that the helpdesk people ("customer support"?) at a large organization like Amazon, Microsoft, or Salesforce would be trained to recognize a mis-directed email from a vendor and send it to the right place, but I don't think that's the claim being made.