[otrs] all notification to be sent from one mail account

Hi all, I need to configure otrs in a way that every notification (creation account,lost password, ticket creation, ticket reply, etc) that is send to customer/agents to be from one mail account. The mail server is sendmail with imap and tls. Where should i add this config? for example: otrs-admin@mycomp.com IMAP and SMTP are mycom.com TLS Thank you. Ec.