Has anyone had reports from clients that they have received invoice reminder emails that were intended for other customers? Any anomalies with email addresses?

Hello qbo12,

Thanks for bringing this to my attention. I've just done some searching on my end and am not seeing any other reports of this issue. Don't worry, I direct you on how to get this worked out and determine what's going on.

The invoice reminder feature is a great option for giving your customers a nudge about their unpaid transactions. You can either manually send reminders to customers from the invoice or customer transaction list by clicking the associated drop-down menu, or you can set up automatic invoice reminders to send at certain times. This article goes over the latter of the two options: Automate invoice reminders in QuickBooks Online

In both cases, the customers should only be seeing reminders for their own invoices. Because they're not, information about which method you're using, your overall setup, and how many times this has happened are details we're going to want to explore to get to the bottom of it. The most effective way to share those details is by contacting support directly using one of the following options.

Schedule a Callback or Chat: click (?)Help in the upper right > click Contact Us > explain your situation > click Let's Talk > choose Get a callback or Start a Chat

Social Media: Facebook, Twitter, and Instagram

The support team member will be able to securely gather your information to determine the next steps to resolve the issue.

Don't hesitate to reach out.