You'll want to review the customer's profile associated with the estimates that you're trying to send out in QuickBooks Online (QBO). I'll provide more details below to help resolve this situation, Tyler.
 

If the customer's profile contains an email address, the system will automatically utilize it as a recipient. That said, the delivery method will be through email. However, if you want all the estimates to be sent via text, you can consider manually copying the link and sending it to your customers in QBO.
 

Feel free to utilize the Reply button if you have other questions or need assistance with specific tasks in QBO. Rest assured, we’ll get back to you as soon as possible.