How should marketing, transactional, and cold emails be separated?

Mailstream separation recommendations:

Transactional (highest protection):

Own subdomain (e.g., notify.tidalmail.com)

Dedicated IP if volume supports

Most conservative practices

Never mixed with bulk marketing

Marketing:

Own subdomain (e.g., news.tidalmail.com)

Can share IP pool with other marketing

Engagement-based sending practices

Isolated from transactional

Cold outreach (highest isolation):

Completely separate subdomain

Separate IP

May need separate root domain

Highest risk, needs maximum isolation

Protect your most valuable streams from your riskiest.

Essential cargo on clean ships. Experimental cargo on isolated vessels.