JSM Customers don't receive email updates

[Edgar Rafii Manzo]

I'm a JSM admin for a project. I've set up a help center where customers can create IT support tickets. The problem is whenever the ticket is picked up and updated, the customers are not updated. I've turned on every customer notifications. One thing I noticed is that on the Customers page, the status are mostly "Invited", and when I clicked 
"Resend Invite", nothing gets sent to their email. What is the cause here? Thanks all.

[Jack Brickey]

Hi @Edgar Rafii Manzo , how do you know no email is being sent? It could be that it is in the app in their spam folder or possibly their email address is blacklisted for some reason. Have you asked one customer to navigate to the help center portal to see if they can access?

[Edgar Rafii Manzo]

I asked a customer to try and submit a ticket, I updated the ticket status to On Progress, left the ticket a comment for the customers. I let the customers know that they should receive emails for the ticket updates, but they didn't, and it's not in their spam folder either. I have tried this with 3 different customers

[Jack Brickey]

Hi @Edgar Rafii Manzo , could you create a test customer account, e.g. using your personal email or create a test gmail account, and then use it to check if you receive notifications. If you do then it is possible that your actual customer domain is blacklisted, if you do not then it is likely a permissions issue.