Agencies send on behalf of many client domains and must isolate reputation per client.
What cold email infrastructure is#
Cold email infrastructure is the set of secondary domains, mailboxes, authentication records, and sending tools used to run outbound campaigns without risking a company's primary domain.
Why it matters#
Cold outreach carries higher complaint risk. Isolating it protects the main domain's transactional and marketing reputation.
Implementation plan for marketing agencies#
- Register 2 to 5 lookalike domains and redirect them to your main site.
- Set up SPF, DKIM, and DMARC on every domain from day one.
- Create 2 to 3 mailboxes per domain and warm each for 3 to 4 weeks.
- Cap sends at 30 to 50 per mailbox per day and rotate across mailboxes.
- Monitor bounce and reply rates per mailbox; retire any that degrade.
Priorities specific to marketing agencies#
Agencies send on behalf of many client domains and must isolate reputation per client. Weight your effort toward the steps above that address this constraint first, and measure with metrics that match how marketing agencies generate value from email.
Common mistakes#
- Sending cold mail from the primary company domain.
- Skipping DMARC on secondary domains because 'they do not matter'.
- Buying aged domains with unknown history.
Frequently asked questions#
How many emails can I send per mailbox per day?
Google Workspace allows 2,000, but for cold outreach 30 to 50 keeps you under behavioral thresholds.
Should I use Google Workspace or Microsoft 365 for cold email?
Both work. Workspace mailboxes tend to warm faster; Microsoft has stricter outbound spam filtering.