We can change the email address showing at the bottom of the invoice sent to clients by going to Partner Center > Administration > Customize > Under partner defaults tab; click on Email Settings > Sender Email->Change it and then apply the changes.
This is also the email address from which the platform will send reports; to which recipients can reply.
For Partners with multiple markets, repeat the same steps under the 'Markets' heading > click the pencil icon to select market and update email accordingly or simply apply the Partner branding configurations to the additional market(s).