The after signup email is a one-time email that is sent to contacts after they've signed up for your campaign. Typically, an after signup email isn't sending because it hasn't been properly enabled as they are disabled by default. 

Troubleshoot after signup emails

To ensure a campaign's after signup email is enabled: 

• Navigate to the Convert > All Campaigns via the main navigation. 
• Select the campaign in need of an after signup email. 
• Select the Follow-Up step in the campaign builder. 
• Enable the desired email(s) by switching the Published? toggle to the ON position. If the campaign is active, the email(s) will start sending to contacts who submit the campaign immediately. Make sure your content is customer-ready before taking this action.

Note: Enabling an after signup email on an active campaign will not retroactively send the email to contacts that have already signed up via the campaign.