Gmail enforces bulk-sender rules: authentication, one-click unsubscribe, and spam-rate thresholds under 0.3% in Postmaster Tools.
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.
Setting up cold email infrastructure for Gmail#
- 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.
How Gmail reports results#
Open a delivered test message in Gmail and view the original or headers. Look for Authentication-Results and any provider-specific verdict headers. Use the provider's sender dashboard for aggregate reputation.
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.
Does Gmail require cold email infrastructure?
Gmail enforces bulk-sender rules: authentication, one-click unsubscribe, and spam-rate thresholds under 0.3% in Postmaster Tools. Treat cold email infrastructure as required for any meaningful volume.