Customers and TSEs often look for information on how to enable the 'Show email details' link which is technically known as 'Sent/Received Emails' on an Activity stream.
See image for below:
The following steps will enable you to view the 'Sent/Received Emails' in the activity stream:
1) Ensure that the following property value has the right role added so the user with the role can view the email option (Show email details)
2) The email sending property (glide.email.smtp.active) should be set to true. Note, it does not matter even if you see emails being sent from Email logs (sys_email), the 'Show email details' will not show unless this property is enabled.
3) If you are testing on an OOB Instance, please set an email address, eg: employee email address just for testing purposes in the system property (glide.email.test.user).
4) Make sure the 'Sent/Received Emails' checkbox is ticked on the Activity Stream filter (see image in description).
Now you can test this by logging a new incident and notice the email activity is now visible in the activity stream.
Note that another alternative on an OOB instance with email sending disabled is to navigate to the sys_email table, locate the emails related to the record you are using and update their type to "sent". These will then show up in the activity stream if 'Sent/Received Emails' is enabled in the Activity Stream filter.
When viewing the email information from other modules, eg: HR you might need to specify roles in the first property.