How can using subdomains help isolate reputation issues?

Subdomain isolation benefits:

Reputation separation:

marketing.tidalmail.com can have different reputation than tidalmail.com

Problems in one do not necessarily contaminate the other

Allows different sending practices per stream

Use cases:

Marketing on subdomain, transactional on root

Different subdomains for different message types

Testing new practices on isolated subdomain

Limitations:

Not complete isolation (some reputation linkage)

Severe root domain issues may affect subdomains

Requires proper authentication setup per subdomain

Implementation:

Set up SPF, DKIM, DMARC for each subdomain

Use appropriate subdomains in From addresses

Configure ESP to send from correct subdomain

Separate divisions of the company with separate reputations.