要約

Whenever a ticket reaches its approval stage, in case the project's customer notification for Approval required is enabled, an email notification is sent to the approvers notifying them that there's a ticket waiting their approval. It usually has the Approve and Decline buttons on the email, however that actually depends on how such notification is set up. In order to check that in a company-managed project you should:

1. From your service project page, select Project settings and then Customer notifications options from the left menu.
2. Scroll down and click the Edit action relating to the Approval required notification. 
3. The Security settings configuration (screenshot below) directly influences if the mentioned buttons will be part of the notification email or not:

For team-managed projects, which has exactly the same configuration, you should reach the configuration page by:

1. From your service project page, select Project settings and then Notifications options from the left menu.
2. Now choose Customer notifications option on the same menu, scroll down and click the Edit action relating to the Approval required notification. 
3. You should get to the same configuration page from the company-managed projects above.

ソリューション

In case you're not receiving the Approve and Decline buttons in the notification you should change the settings above to one of the other two possible options, depending on your use case:

• Approvers must be signed in to use 'Approve' and 'Decline' buttons - If this options is selected, as soon as you hit one of the buttons you will be prompted to the customer portal login page in case you're not authenticated.
• Approvers can use 'Approve' and 'Decline' buttons without being signed in - In case this option is selected, by hitting one of the buttons you will perform the action even if not logged in.