Hello @Nebraskabison,

Thanks for sharing your question with the Klaviyo Community!

I would first question weather your campaign was scheduled using either the Deliver messages according to recipient's local time or Batch sending sending methods. Using either one of these sending options would cause your emails to be delivered in a delayed manner. Using the Deliver messages according to recipient's local time option will send your campaign to each recipient based on their respective timezone. Therefore a campaign send may take upwards of 24 hours to fully be completed for every available timezone. On the other hand, Batch sending —  will split your email send into smaller batches and send over a length of time of your choosing. If you had selected a longer time frame, this may cause the campaign to send at a later point in time. You can learn more about these sending options from the Email Campaign Schedule and Send Options Help Center article.

In addition, if you were not using either of these sending options, another potential cause may be your emails being deferred causing your emails to be delivered late. Emails are deferred when the receiving inbox provider delays accepting the message. This does not necessarily mean that your email will not be delivered, but rather that it won’t be delivered immediately. This can happen for a variety of reasons, but some of the most common reasons for this include too many spam complaints on the email or technical issues with the receiving inbox server. Keep in mind that if you have a spam complaint rate greater than 0.08%, we recommend taking action to correct this as continued decreasing KPIs can have long term negative impacts on your deliverability and sending reputation. To learn more about this, I would suggest taking a look at the How to Monitor Email Deliverability Performance and How to Strengthen Your Sender Reputation Help Center articles. 

I hope this helps!

David