Is not sending cofirmation emails

[info...@gmail.com]

Hi! I've been using Form Postman for almost 2 years with no problem until 2 weeks ago when the app is not sending the confirmation email I saved.  When a client of mine fills up an application form in my website, this App used to send an email with all the instructions to join my products, however, this is not happening.  Please let me know what am I doing wrong.  Thanks.