If you want to check how your email would look like in Lead's Inbox, you can send a test email from your campaign.
To do this, follow this quick steps.
On your Sequences section, click Preview.
Add the email address which you want the test email to be sent. Use commas to separate the email address.
Click Send test email. The test email will be send to all the email address listed.
If you encounter an error when sending a test email from the campaign, please kindly check if the sending account you're using is active.
If you're getting the same error even using another sending account, please share the screenshot of the error with our chat support for further assistance.