The first of three International Society for Molecular Plant–Microbe Interactions (IS-MPMI) eSymposia was convened on 12 and 13 July 2021, with the theme “Molecular Mechanism & Structure—Zooming in on Plant Immunity”. Hosted by Jian-Min Zhou (Beijing, China) and Jane Parker (Cologne, Germany), the eSymposium centered on “Top 10 Unanswered Questions in MPMI” number five: Does effector-triggered immunity (ETI) potentiate and restore pattern-triggered immunity (PTI)—or is there really a binary distinction between ETI and PTI? Since the previous International Congress of IS-MPMI in 2019, substantial progress has been made in untangling the complex signaling underlying plant immunity, including a greater understanding of the structure and function of key proteins. A clear need emerged for the MPMI community to come together virtually to share new knowledge around plant immunity. Over the course of two synchronous, half days of programming, participants from 32 countries attended two plenary sessions with engaging panel discussions and networked through interactive hours and poster breakout rooms. In this report, we summarize the concerted effort by multiple laboratories to study the molecular mechanisms underlying ETI and PTI, highlighting the essential role of plant resistosomes in the formation of calcium channels during an immune response. We conclude our report by forming new questions about how overlapping signaling mechanisms are controlled.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .