The setup I’d use if I were starting over:
2) 3-5 mailboxes per domain
SPF, DKIM, DMARC configured
3) 2-3 weeks of warm-up with Instantly or Smartlead, then 20-25 emails per mailbox
Bonus: keep Outlook mailboxes separate from Google Workspace or custom ones, and send fewer from the Outlook ones.
I learned the volume limit the hard way. I raised sending from 25 to 30 per mailbox and burned all 30 mailboxes. Recovery took 1-2 weeks of re-warming.
What’s your current setup (tool, mailboxes per domain, daily volume)?
Share it and I’ll tell you what I’d tweak.