Hey @diegoeche,

Great question!! I asked a similar question mainly focused on phone numbers here: 

I also asked this as a support question and they got back to me with this response:

Zack here from Klaviyo support. Thanks for reaching out, and I'd be happy to assist!
 
I see that you had reached out through our Community recently about an issue you were seeing with bulk loads that encountered errors due to a bad email/phone number. I've had a chance to touch base with my team about this, and we don't exactly have a list of values that aren't accepted. With that being said, Phone Numbers synced must be in E.164 format, and Emails must contain an @ to be considered valid.
 
There isn't any pre-built logic we have to exclude those invalid email/phone numbers. One suggestion would be to either build out, or work with your developers to build, conditional logic that will remove any profiles who don't have the accepted formatting I mentioned above. So long as this occurs prior to the bulk API request, then this should mitigate issues where the entire request fails for one bad value.
 
I'd also be happy to provide any feedback for my team, or write a feature request on your behalf. Just let me know in a response with any feedback and more details about your use case, and I can take next steps. Otherwise, let me know if you have any further questions or concerns, and have a great day!

Best,
Zack at Klaviyo Support

I didn’t find either of these answers to be conclusive or satisfactory so I’m hoping you’ll get a better response!

Cheers,

Kevin.

I’ve had the most trouble with emails that have initial or trailing spaces.  That’s easy to fix but frustrating to identify.

HI @KeviSunshine, @stem and @diegoeche!

I’m going to check on this with our API team and I’ll update the thread ASAP!

Best,

Brian

Any news on this? It's been 6 months