Use this SMTP test tool or this one to check if your SMTP setup is working before contacting the support. If the tests fail, consider the following solutions.
Your SMTP is not enabled
Go to your email provider and make sure you have SMTP sending and POP/IMAP receiving enabled.
Your username is not your email address
In most cases your username is the same as your email address
For some providers your username is different. Please check with your provider how they structure the username in their SMTP help articles
Your email provider requires you to create an app secure password
Providers such as Gmail, AOL, hotmail, Yahoo require you to set up app secure passwords in order to use SMTP services. Please set them up directly with your providers.