This is puzzling me. The other user and I tried to send invoices via the Email button under the Communication subtab. The email he sends shows the Root Parent Subsidiary as the sender. On my end, it uses the actual Subsidiary. Both of us do not have a nickname or a from email address on the Set Preferences. The Return Email Address preference is also set to Subsidiary Return Email Address in the email preferences. So my email is correct. Why does his email use the root parent as the sender?

the user has a different subsidiary than yours on their employee profile?

Yes, but his is not the root parent. It's a completely different subsidiary