Hello @Maine Jewelry,

Welcome to the Community and thanks for your question.

Without being able to go into your account and look into your flow settings, setup, account, etc. I am going to go off what I think might be happening. 

There are two types of bounces:

 
A hard bounce occurs when an email cannot be delivered due to a permanent reason. This could be caused by a variety of reasons, including a misspelled email. Klaviyo automatically suppresses any email address that hard bounces.
A soft bounce is always caused by a temporary reason, such as when a recipient's inbox is full or when their email server is momentarily down. If an email soft bounces more than 7 consecutive times, Klaviyo will suppress this address.
 

There are several possible reasons why an email address may hard or soft bounce including that the email address doesn’t exist, their mailbox is full, they have auto-reply turned on, or the server blocked the incoming email. 

Viewing Hard Bounce and Soft Bounce Metrics

To see overall bounces across all campaigns, view the Campaign Trends Report. Additionally, you can use segments to identify addresses that have hard or soft bounced.

It could be that if you are using a send from address such as gmail or yahoo, then it would bounce some users because you might not be authorized to use the from-address domain set for the emails.
 
If this is the case:

To resolve this, change the default from Email, so when you create future campaigns or flows this new one will be used. You can do this by visiting this page in your account.
After that step, you will want to update all current flows and future scheduled emails. This is because changing the default from address will not apply to currently existing/scheduled emails retroactively.

I also checked with a Support team colleague and did see that your ticket was responded to. If you are not seeing their responses, please check your spam.

Thanks,

Alex

Hi Alex,

It turned out to be that I had an @yahoo address on the account. I find it frustrating that Klaviyo does not edit this field on the account page - if that sort of an address cannot be used then it should be edited and at the very least a warning message should be displayed. Also frustrating that the Klaviyo system knows it rejected because of the address but doesn’t inform the user. As a beginner struggling to understand a complex application, these sorts of things would be very helpful.