Open rates of 70%, 100%, and 0% in test accounts provide varying insights into email campaign performance. A 70% rate can indicate strong engagement, but should be compared against industry benchmarks for context. A 100% open rate frequently points to issues within the testing setup like caching, automated opens, or whitelisting, and is not a reliable indication of real-world results. A 0% rate generally signifies deliverability problems, often due to spam filters, poor sender reputation, or failure to comply with email authentication standards (SPF, DKIM, DMARC). Factors like spam traps, similar testing environments, and bulk email guidelines also play a significant role in skewing data. Thus, test account open rates need cautious interpretation, consideration of industry benchmarks, and a focus on ensuring proper authentication and deliverability.