This is unrelated to any mailing-list change, since both were sent from/to the 10991049.xt.local mailing list.
Search for the header entry `List-ID: <10991049.xt.local>` in your Sep 4 email. If it came from that list, the one from Aug 25 will very likely have been lost during transit.
I use their products in the 10-user license program since 2016 and got automatically subscribed to their mailing list back then, and never made some change to the subscription. I'm receiving emails from that list since 2020-10-17.
On the 2020-07-10 I got a mail from them telling me:
```
Subject: Please double-check your contact details for Atlassian
Making sure you don't miss important emails
Hi,
When you purchased your Atlassian products, we asked for the contact information for two types of people in your organization:
Billing contact - A person we contact with invoice and billing information
Technical contact - A person we contact about product changes, security advisories, etc.
We don't want your company to miss out on important information from Atlassian, so please take a minute to make sure your contact information is current. Here's what we have in our system:
```
