Hi Max,
The retention tags will not appear in a specific email. You can use retention tags to create retention policy rules. You can use retention policy rules to help you manage emails, like archiving emails to archive folder.
You could refer to the steps below to check the retention policies and retention tags that can be used in your company:
1).Logon to Office 365 portal.
2).Click on Outlook at the top of the Admin page. This will open your Outlook mailbox through Outlook Web App.
3).Click Options from the right up corner and click See All Options.
4).From the Options menu, open Manage My Organization.
5).Click Mail Control in the navigation pane in the left.
6).Click Retention Policies to check the available retention policies in your company.
Click Retention Tags to check the available retention tags in your company.
Additionally, you can refer to the steps below to check which retention policy has been used for a specific user:
1).Logon to Office 365 portal.
2).Click on Outlook at the top of the Admin page. This will open your Outlook mailbox through Outlook Web App.
3).Click Options from the right up corner and click See All Options.
4).From the Options menu, open Manage My Organization.
5).You are now on the Users & Groups page, select an account and click on Details.
6).Click Mailbox Settings and check the retention policy which has been used for this user.
Please refer to the links below to get more information about retention policy :
Set Up and Manage Retention Policies in Exchange Online with Windows PowerShell:
http://help.outlook.com/en-us/140/gg271153.aspx
Retention Tags in Exchange Online:
http://help.outlook.com/en-US/140/ms.exch.ecp.learnmoreretentiontags.aspx#managemrm
Create a New Retention Tag:
http://help.outlook.com/en-US/140/ms.exch.ecp.newretentionpolicytag.aspx
Thanks,
Linda Wang