Allow for custom emails being sent to welcome new users

Problem statement

The latest new user email read as follows:

Subject: [Atlassian] USERNAME, welcome to Atlassian OnDemand
Sent by: jira@example.atlassian.net

Message: Your OnDemand account has been created! Atlassian OnDemand is the à la carte hosted development and collaboration solution for teams building great software. Log in now to track your issues and tasks, collaborate with your team, and stay on top of project activity.

• Receiving emails from jira@example.atlassian.net can be confusing when invited users will only use Confluence.
• This causes support issues as the new user email is getting ignored or deleted by users.

Suggested solution

1. Can the invitation be sent from cloud@example.atlassian.net?
2. Can the message be more generic - not every Cloud customer is using it for "building great software". I've attached the old Confluence OnDemand invitation for reference: confluenceinvitemessage.png.

Ideally, the Cloud site administrators should have the ability to create a custom message template.
We actually send out a 2nd follow up message to this invitation that also cover tips such as reminders to set their time zone, setting a default landing page, notifications and where to get more help.