I would like a mail message goes out to other subscribers that have listings in the users searched area if you have the option to solicit a mass “I’m headed your way” request and everyone that is within that area or city will receive an email to reach out to that member.
To send bulk emails you’ll definitely need to integrate service like: Mailchimp, Sendgrid or something similar.
As far as workflow goes, you’ll just need to decide when/how this action will be triggered. Then you’ll find Send Emails in the workflow Actions and that’s it, in a nutshell.