How to setup an email alias
To send emails from another email address in your Close.io account you can setup an alias. In most cases this should only be used if the alias is on the same domain. For instance if your email account is email@example.com and you want to send email as firstname.lastname@example.org too. If you're looking to send emails from a different domain you may want to setup a separate email account in Close.io so that you can use that domain's SMTP credentials.
To get started head to Settings -> Email Settings and look for the following option:
Note If you're using Google Apps / Gmail you need to set up your alias within that system first. Instructions here.
Email aliases can also be used to indicate that a particular email address belongs to the organization, which helps Close.io determine whether an email was incoming or outgoing, and is also used to filter out intra-company communication.