|Available in: Professional, Enterprise, Performance, Unlimited, and Developer Editions|
To enable this feature, from Setup, enter Send through External Email Services in the Quick Find box, then select Send through External Email Services.
You can allow your org to send through either Gmail or Office 365; you can’t select both.
This feature is enabled for all users with the standard user profile or with the “Send Email through External Email Services” user permission.
When your users send emails using the Lightning Experience email composer, the emails go through Gmail or Office 365 using the OAuth industry standard. User credentials aren’t stored within Salesforce.
Users can manage their email configuration from My Email Settings within their personal settings. The My Email Settings page gives users the option to send through their external account, and customize the name and signature that appears on outgoing emails.
Emails sent through workflows and triggers are still sent through Salesforce. Also, bounce management isn’t supported when you send through external email accounts.
If you send email through Gmail or Office 365, Transport Layer Security (TLS) is handled through the external email service and not through Salesforce settings. Also, email delivery information for Send through Gmail or Office 365 is not available in the email logs. Email logs should be obtained from Gmail or Office 365 instead.
For more information about different email solutions, see Which Email Setup is Best for My Org?