run through this for your biggest client account right now. takes 5 minutes.

• [ ] all sending domains have SPF, DKIM, and DMARC configured
• [ ] no cold email is being sent from the client's primary business domain
• [ ] inboxes have been warmed for 14+ days
• [ ] sending volume is under 15 emails per inbox per day
• [ ] inboxes are split across Google and Outlook (not all on one provider)
• [ ] you can see which sending IPs each inbox is on
• [ ] no IPs are on any blacklist (check mxtoolbox.com/blacklists)
• [ ] you have a clear process for rotating inboxes when they degrade

score: if you ticked 6+, your setup is solid for that client. if you ticked fewer than 5, fix that account before adding more clients. scaling on broken infrastructure just scales the problems.