I can give a JSD Project a name. For example "Atlassian-Gold-Partner". If I set the customer permission to: "Anyone can email the service desk or raise a request in the portal" and send an email to the JSD project I get an welcome mail from "Atlassian-Gold-Partner@domain.com".
If I change the project name to "Atlassian-Platinum-Partner" the senders name is still: "Atlassian-Gold-Partner@domain.com". So in other words there is no configuration to change the senders name again.
I guess this is a bug. Is there a workaround available? Does someone know, where to change it in the database?