Analyzing emails from over 100 B2B companies, Esther-Grace Okonkwo identified common mistakes that can lead to poor email marketing performance. She recommends avoiding sending new subscribers multiple sales pitches at once by creating an onboarding sequence that builds trust and introduces them to the company's values and culture. Boring subject lines should be avoided in favor of attention-grabbing ones, while the "Rule of One" suggests writing copy with one specific reader, big idea, offer, and promise to avoid decision paralysis. Formal language can also be a barrier, so emails should be written like a 1:1 conversation. Finally, segmenting the list and creating an email map before sending hyper-relevant emails is crucial to avoid sending irrelevant emails. By avoiding these common mistakes, B2B companies can improve their email marketing performance and increase conversions.