I want to use a mail campaign software that syncs with quickbooks. ideally 2 ways so any data added into either appears in the other...What do you recommend?

Hello ianpaull,

Welcome to the Community - thank you for your question.

We cannot recommend any third party apps - you can have a look at the apps that are designed to work with QuickBooks through the following link: https://apps.intuit.com

Thanks,

Talia