Improving Client Retention: Evaluating Email Tools and Strategies

Hey team, I acquired an agency 6 months ago with an insanely high client churn (long story), and came to realise that their process and infrastructure was based on best practice maybe 4 years ago. They’re not even sending ESP-to-ESP. They also use Quickmail, which seems to be having trouble with Outlook inboxes. Would I be right in switching to Instantly or Lemlist asap (as part of a broader effort to fix our stack), or is that a bit knee-jerk? Where would the quick wins be? We’re only JUST adopting Clay 😬