Please note: The following information pertains to the HubSpot mobile app on iOS.
If you have connected your inbox in the CRM, emails sent through the mobile app will be sent from that connected email address. When using a connected inbox, you will also be able to use HubSpot Sales features such as your email signature and templates.
If you have not connected your inbox in the CRM, emails sent using the HubSpot mobile app will send emails through the Apple Mail app on your iPhone using the email address you have set as default.
If you'd like to use another email address as the from address for emails sent using the HubSpot mobile app and have not connected an inbox, you can add that other email account to your mail app and select that as your default address on your iPhone (Settings > Mail > Default Account).