E-mails sent via QuickBooks do not appear in the sent emails

Hello there. @Praveen_Uduweriya.

Let's go to the Sent Email tab in the Customer Center so you can check the emails you've sent to your customers in QuickBooks Desktop (QBDT).

When you set up your email service in QBDT to send emails to your customers, you should be able to view their copy in the Customer Information window's Sent Email tab. To do this, here's how: 

1. Go to the Customers menu.
2. Select Customer Center.
3. Find and click the name of your customer.
4. On the Customer Information page, go to the Sent Email tab.
5. Set the Date. 

You can read this article to learn more about sending transactions through Webmail or Outlook in QBDT: Connect your email to QuickBooks Desktop.

Also, you may want to check out this article as your reference to guide you in learning the different ways you can track customer transactions in QBDT: Customer transaction workflows in QuickBooks Desktop.

Let me know if there's anything else you need about managing customer transactions in QBDT. I'll gladly help. Take care, and have a great day, @Praveen_Uduweriya.