Q:

Send an Azure AD B2C Welcome Email

I've created a Xamarin. Forms App that is integrated with Azure AD B2C for user sign in.   Since you can't create custom validation emails with Azure AD B2C, I've turned email validation off.   However, I'd still like to have the ability to send a basic introduction email to my users when they sign up.   
Is there an easy way to add an email address to a contact list when a user is added to the directory and then automatically send them a welcome email using an automated email service such as MailChimp?   If so, how do I set that up? 

A:

Azure AD B2C does not have any support for custom emails events or custom triggers through its built-in policies. 
However, you can use Azure AD B2C custom policies to call out to a REST API that sends an email as part of the authentication flow.  You can easily implement this REST API using an Http Triggered Azure Function. 
Check out the sample code for such Azure function in the sample SendMailWebHook function. 
You can also request support for custom email events in the Azure AD B2C feedback forum

