Edge automatically sends emails in response to certain events. For each of these events, Edge
  defines a default email template in /opt/apigee/edge-ui/email-templates. To
  customize these emails, you can edit the default templates.
The events where an email is sent, and the default template file for the generated email, are:
- New user is added: 
user-added-new.html - Existing user requests a password reset: 
password-reset.html - A user is added to an organization: 
user-added-existing.html 
The "From" field of the email can be set by using the
  conf_apigee_apigee.mgmt.mailfrom property in
  /opt/apigee/customer/application/ui.properties (if that file does not exist, create
  it). For example:
conf_apigee_apigee.mgmt.mailfrom="My Company <myCo@company.com>"
The email subjects are customizable by editing the following properties in
  /opt/apigee/customer/application/ui.properties (if that file does not exist, create
  it):
conf_apigee-base_apigee.emails.passwordreset.subjectconf_apigee-base_apigee.emails.useraddedexisting.subjectconf_apigee-base_apigee.emails.useraddednew.subject
Several email properties reference the {companyNameShort} placeholder, which
  defaults to a value of "Apigee". You can set the value of the placeholder by using the
  conf_apigee_apigee.branding.companynameshort property in
  ui.properties. For example:
conf_apigee_apigee.branding.companynameshort="My Company"
After setting any properties in /opt/apigee/customer/application/ui.properties,
  you must restart the Edge UI:
/opt/apigee/apigee-service/bin/apigee-service edge-ui restart