Hi @Tarak, welcome to the community!

This could be a number of issues, but most likely you may want to double check a few items:

• Are your emails in your Flows/Campaigns coming from the same domain as your site? For example, if you signed up with Klaviyo using a gmail account, that may be the default email on record for your reply-to email adderess.
• If you are using a branded domain, did you complete the process to make sure you have the correct settings in your DNS (registrar).  
• Where did these email come from?  Are they users that signed up and provided consent for your marketing emails? 
• If you added these emails manually, or imported them, double check to make sure those emails are valid email addresses.  I’ve seen import errors where the First Name was in the “Email Address” column and was not properly uploaded.
• Since there are only 6 + 2 emails that had Technical/External errors, see if you can look at their profile in Klaviyo to find other clues that may have caused it.  

Hope this helps!

I haven't added the domain yet into Klaviyo. After seeing your reply, I have updated my klaviyo domain.  

After adding the domain to Klaviyo.  Klaviyo System Shows me to Verifying the domain And it will take 48 hours.

Klaviyo hasn't sent any email to my customer yet since I started. Does this happen for my domain setting?

@Tarak it can take up to 48 hours but in many cases is much faster. Is this still an issue for you?

it's was unify within an hour. Thanks for your reply.