You also have the ability to 'Approve & Complete' the 'Intro Lyne' from the 'Contact Details' page. You can even access the 'Contact Details' page from the same pop-up by clicking on the contact's name that shows upon clicking the 'Intro Lyne' task generated in the 'Sales Inbox'. (see the below screenshot)
Once the 'Contact Details' page opens, you will see the 'Intro Lyne' record history. Click the 'checkmark' icon highlighted on the contact details page in the below screenshot to Edit, Approve or Complete the generated Intro Lyne.
On clicking the 'checkmark' icon, it will open up the same pop-up from where you can follow the same 'steps to Edit, Approve & Complete an Intro Lyne from the Sales Inbox' under the article 'How to Edit, Approve & Complete an Intro Lyne from the 'Sales Inbox' within Uptics'
An 'Approved & Completed' Intro Lyne under the 'Contact Details page will look as highlighted in the screenshot below.