An independent technical analysis of the email infrastructure powering one of the industry's most popular marketing tools.
Overall GradeD+
Key Findings
Shared-domain, shared-IP architecture on Twilio SendGrid's shared pool tier
Zero contractor control over authentication, domain reputation, or sending infrastructure
Emails routinely landing in spam for contractors paying $1,000–$3,000/month
Section 2: Infrastructure Analysis
The platform routes all customer email through a shared SendGrid sub-account, meaning every contractor's campaigns share IP reputation with thousands of other senders. Authentication records (SPF, DKIM, DMARC) are configured at the platform level, not at the individual customer level, resulting in...
Our testing revealed that 47% of test messages sent through this infrastructure were flagged or filtered by major mailbox providers. The root cause traces to shared-IP warm-up cycles and inconsistent sending patterns across the pool...
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